Image collation method and apparatus for excluding combinations of coordinate values

ABSTRACT

A plurality of linear images are cut, the cut linear images are scanned successively on other images to detect positions where the degree of similarity is high, and these detected coordinate values are partially combined, and when the image is collated, combinations which does not satisfy the relative positional relation corresponding to these linear images are excluded from the processing target with reference to the relation between coordinate values of the detected positions. The image collation device thus enables a fingerprint collation device to obtain collation result consistently within a short time.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an image collation device, which is applied,for example, as a fingerprint collation device. The device of thepresent invention involves the operation that a plurality of linearimages are selected, the selected linear image is scanned successivelyon another image to find the portion similar to the original image, andbased on the relation of the coordinate value of the position of thedetected portion, these detected coordinates are combined partially forcollation of the image, and combinations which do not satisfy therelative positional relation corresponding to the linear images areexcluded from the processing target which is to be subjected tosubsequent processing, thereby the image collation device can obtain thecollation result consistently within a short time.

2. Description of the Related Art

Heretofore, in the conventional fingerprint collation device using animage collation device of this sort, featured points such as a branch,point, and cut (referred to as featured point hereinafter) are extractedfrom a fingerprint image obtained by means of an image pick-up device,and fingerprint collation is performed with reference to these featuredpoints.

In other words, in the conventional fingerprint collation device, afingerprint to be collated is previously converted to database withreference to, for example, featured points and coordinate values. Afingerprint image to be subjected to fingerprint collation is subjectedto image processing in order to extract featured points. Then, adatabase has an access to the extracted featured points and thefingerprint is collated based on the existence of corresponding featuredpoints.

The conventional fingerprint collation is disadvantageous in thatfingerprint collation takes a long time. If fingerprint collation iscarried out consistently within a short time, the fingerprint collationdevice provides improved convenience for use, and such improvement isdesirable.

SUMMARY OF THE INVENTION

The present invention has been accomplished in view of such disadvantageof the conventional fingerprint collation device, and this inventionprovides an image collation device which is capable of collating animage such as fingerprint consistently within a short time.

To solve such problem, in the present invention, by detectingcombinations corresponding to the relative positional relation of thelinear images from combinations of detected coordinates, coincidencebetween images is judged, wherein when combinations are formed using thedetected coordinates, partial combinations are formed, coordinate valuesfor each partial combination is judged, and based on the judgmentresult, combinations of coordinate values which do not satisfy therelative positional relation of the linear images are excludedpreviously from the processing target.

When detected coordinate values are combined and combinationscorresponding to the relative positional relation of the linear imagesare detected, combinations of coordinate values which do not satisfy therelative positional relation are excluded previously from the processingtarget with aid of the partial combinations, thereby the number of finalcombinations is reduced by the above-mentioned previous exclusion, thusthe processing is simplified as a whole in spite of increase ofprocessing for forming the partial combinations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram for illustrating the whole structure of afingerprint collation device in accordance with the present invention.

FIG. 2 is a block diagram for illustrating a fingerprint data inputsection of the fingerprint collation device shown in FIG. 1.

FIG. 3 is a schematic diagram for illustrating an image of a fingerprintof the fingerprint data input section shown in FIG. 2.

FIGS. 4A to 4E are signal waveform diagrams for describing correction oflight quantity dispersion in the fingerprint data input section shown inFIG. 2.

FIG. 5 is a plan view for illustrating the relation between an image andsegments of a fingerprint.

FIGS. 6A and 6B are signal waveform diagrams for describing correctionof actual light quantity dispersion.

FIGS. 7A to 7C are signal waveform diagrams for describing correction ofa threshold value served as the reference voltage.

FIGS. 8A and 8B1 to 8B3 are signal waveform diagrams for describingswitching of a threshold value served as the reference voltage.

FIG. 9 is a block diagram for illustrating a fingerprint collationmemory and fingerprint database together with peripheral circuits.

FIG. 10 is a schematic diagram for illustrating a fingerprint image ofthe fingerprint data input section shown in FIG. 2.

FIG. 11 is a schematic diagram for illustrating an image that thefingerprint image shown in FIG. 9 is rotated.

FIG. 12 is a block diagram for illustrating an image rotation circuitshown in FIG. 9.

FIG. 13 is a schematic diagram for describing image rotation by means ofthe image rotation circuit shown in FIG. 12.

FIG. 14 is a schematic diagram for illustrating an image after rotationcorresponding to FIG. 13.

FIG. 15 is a schematic diagram for illustrating the content of thefingerprint database.

FIG. 16 is a block diagram for illustrating a finger prints.

FIG. 17 is a schematic diagram for describing cutting into linearimages.

FIG. 18 is a schematic diagram for describing the supply of fingerprintdata to linear images.

FIG. 19 is a schematic diagram for illustrating the content of acoordinate group memory.

FIG. 20 is a flow chart for describing processing sequence of the systemcontrol circuit.

FIG. 21 is a flow chart for describing optical system operationconfirming processing shown in FIG. 20.

FIG. 22 is a flow chart for describing fingerprint registrationprocessing shown in FIG. 20.

FIG. 23 is a flow chart for describing actual registration processingshown in FIG. 22.

FIG. 24 is a flow chart for describing the continuation of the sequenceshown in FIG. 23.

FIG. 25 is a flow chart for describing effective area detectionprocessing shown in FIG. 23.

FIG. 26 is a schematic diagram for describing the effective areadetection processing shown in FIG. 25.

FIG. 27 is a flow chart for describing finger placing place judgmentprocessing shown in FIG. 23.

FIG. 28 is a flow chart for describing zoom processing shown in FIG. 23.

FIG. 29 is a flow chart for describing threshold value correctionprocessing shown in FIG. 23.

FIG. 30 is a flowchart for describing blackening processing shown inFIG. 23.

FIG. 31 is a flow chart for describing angle detection processing shownin FIG. 23.

FIG. 32 is a schematic diagram for describing the subsequent processingshown in FIG. 31.

FIG. 33 is a schematic diagram for describing the continuation of theprocessing shown in FIG. 32.

FIG. 34 is a flow chart for describing registration data selectionprocessing shown in FIG. 24.

FIG. 35 is a flow chart for describing correlation value detectionprocessing shown in FIG. 34.

FIG. 36 is a flow chart for describing the continuation of theprocessing shown in FIG. 35.

FIG. 37 is a flow chart for describing the continuation of theprocessing shown in FIG. 36.

FIG. 38 is a flow chart for describing the continuation of theprocessing shown in FIG. 37.

FIG. 39 is a schematic diagram for describing linear image cutting froma rotation image.

FIG. 40 is a schematic diagram for describing the supply of afingerprint data to the linear image of a rotation image.

FIG. 41 is a flow chart for describing fingerprint registrationprocessing shown in FIG. 20.

FIG. 42 is a flow chart for describing the continuation of theprocessing shown in FIG. 41.

FIG. 43 is a graph for describing the gradual falling down of thecollation rate.

FIG. 44 is a schematic diagram for describing shifting of a frame. FIG.45 is a flow chart for describing fingerprint data input processingshown in FIG. 41.

FIG. 46 is a flow chart for describing zoom processing shown in FIG. 45.

FIG. 47 is a flow chart for describing comparison judgment processingshown in FIG. 41.

FIG. 48 is a flow chart for describing the continuation of theprocessing shown in FIG. 47.

FIG. 49 is a schematic diagram for describing inclination correction.

FIG. 50 is a schematic diagram for describing image data processing inthe inclination processing shown in FIG. 49.

FIG. 51 is a schematic diagram for describing the supply of afingerprint data to inclination corrected linear images.

FIG. 52 is a schematic diagram for describing the case of a rotationimage shown in FIG. 51.

FIG. 53 is a schematic diagram for describing angle switching.

FIG. 54 is a schematic diagram for describing frame switching.

FIG. 55 is a schematic diagram for describing coordinate values on anerect image.

FIG. 56 is a schematic diagram for describing coordinate values on arotation image in relation to the erect image shown in FIG. 55.

FIG. 57 is a schematic diagram for illustrating the relation betweencoordinate values detected from each frame.

DESCRIPTION OF THE PREFFERED EMBODIMENTS

Embodiments of the present invention will be described in detailhereinafter with reference to the drawings.

(1) Structure of the Embodiment

(1-1) Whole Structure

FIG. 1 is a block diagram for illustrating the whole structure of afingerprint collation device in accordance with an embodiment of thepresent invention. In this fingerprint collation device 1, a systemcontrol circuit 3 controls all the operations in response to useroperations inputted through a key input section 2, thereby, the systemcontrol circuit 3 fetches previously fingerprint collation data D1 of adesired user from a finger print data input section 4, and storesfetched fingerprint data D1 with other user data in a memory toconstruct a fingerprint database 5.

A user inputs a request for fingerprint collation to the fingerprintcollation device 1, a fingerprint data D2 to be collated is fetched fromthe fingerprint data input section 4, and the fetched fingerprint dataD2 is temporarily stored in a fingerprint collation memory 6. Then, thefingerprint data D2 temporarily stored in the fingerprint collationmemory 6 and the corresponding fingerprint data D1 registered in thefingerprint database 5 are inputted to a collation rate detection device7 in response to a user operation inputted through the key input section2. Further, the degree of collation between these fingerprint data D1and D2 is detected, and the system control circuit 3 judges whetherthese fingerprint data D1 and D2 are coincident or not coincidentdependently on the degree of coincidence.

The fingerprint collation device 1 judges whether a fingerprint data D1in form of database specified by the user ID inputted by a user andanother fingerprint data D2 inputted through the fingerprint inputsection 4 are in coincidence, thereby judges whether the user whorequested fingerprint collation is the person to be addressed, andoutputs the judgment result. The fingerprint collation device 1 performsupdating processing of the fingerprint database 5 as requireddependently on the degree of coincidence and records the collationresult. In the fingerprint collation device 1, a message is informed tothe user using a display 8, and a necessary indication is informed tothe user, for example, so that the user is pressed to input a user ID.

(1-1) Fingerprint Data Input Section

FIG. 2 is a block diagram for illustrating the fingerprint data inputsection. In the fingerprint data input section 4, a fingerprint ispicked up as an image from a finger of a user who puts the finger on aprescribed finger placing position through a certain optical system, andfingerprint data D1 and D2 are generated from the image pick-up result.

The optical system comprises a isosceles triangle prism 11 which is heldso that a finger to be subjected to fingerprint collation is placed onits base, a light source 12 for illuminating the base from an inclinedplane of the isosceles triangle prism 11, and a CCD camera 13 forimage-picking up the light illuminated from the light source 12reflected on the base from the residual inclined plane.

In the optical system, as for the portion where skin is not in contactwith the base of the isosceles triangle prism 11, the illumination lightemitted from the light source 12 is reflected totally and guided to theCCD camera 13, and on the other hand, as for the portion where the skinis in contact with the base of the isosceles triangle prism 11, theillumination light is reflected irregularly and the illumination lightis not incident upon the CCD camera 13. As the result, the opticalsystem outputs occulting image corresponding to the pattern of thefingerprint in video signal SV format as shown in FIG. 3 from the CCDcamera 13.

In this embodiment, the CCD camera 13 picks up a finger so that theimage direction from the tip to the foot of the finger corresponds tothe resulting finger image disposed horizontally with the aspect ratioof 4:3. In this case, the blank portion outside of the finger isimage-picked up at high brightness level because the finger is not incontact with the base of the isosceles triangle prism 11.

A comparison circuit 14 converts the video signal SV to a binary signalS1 and outputs the binary signal Si. A latch circuit 18 samples thebinary signal S1 at a timing corresponding to each pixel of the CCDcamera 13 with reference to a clock outputted from a timing generator(TG) 19, and outputs 1 bit image data DV1. A thinning circuit 20 fetchesintermittently the image data DV1, thins the image data DV1 at a certainproportion, and outputs it, and the serial parallel converter circuit(S/P) 21 fetches the 2 bit image data DV1 in 8 byte unit and outputs itintermittently, thereby converts the 1 bit×8 bytes image data DV1 to the8 bits×1 byte fingerprint data D1 or D2 and outputs it to a data busBUS.

(1-1-1) Light Quantity Correction

The comparison circuit 14 generates a binary signal S1 with reference toa reference voltage REF generated from a reference voltage generationcircuit 15, and corrects the light quantity dispersion of the opticalsystem with reference to this reference voltage REF in this embodiment.

In detail, as shown in FIGS. 4A to 4E with a reference of horizontalscanning period, if such optical system generates light quantitydispersion, the signal level of the video signal SV that is the imagepick-up result fluctuates due to the light quantity dispersion (refer toFIG. 4A), thereby, in the case of binary conversion with reference to aconstant reference voltage SL, the binary signal S1 is generated so thatthe time period while the signal level rises is shortened at theperipheral portion where generally the light quantity decreases (referto FIG. 4B). Therefore, it becomes difficult to generate the correctbinary signal, and the fingerprint collation accuracy is deteriorated.

To cope with this problem, in this embodiment, the signal level of thevideo signal SV is detected while a fingerprint is not image-picked up(refer to FIG. 4C), thereby the optical system detects the lightquantity dispersion. A reference voltage REF is set by setting off thedetected signal level to the zero level side by the prescribed value,and a binary signal is generated with reference to the reference voltageREF (refer to FIGS. 4(D) and (E)). As described herein above, the lightquantity dispersion is corrected and the fingerprint collation accuracyis improved in the fingerprint collation device 1. Further, thefingerprint collation device 1 detects soiling of the place where afinger is placed and deterioration of the light source 12 based on thecomparison between the reference voltage REF in stand-by condition andthe image pick-up result, and generates an alarm, thereby also thefingerprint collation accuracy is improved.

In detail, in this embodiment, an image outputted from the thinningcircuit 20 is divided with an equal interval in the horizontal directionand vertical direction in 8 byte unit as shown in FIG. 5, thereby aplurality of segments are formed. The reference voltage generationcircuit 15 comprises a latch circuit for holding the reference data ofeach segment and a digital analogue conversion circuit for performingdigital analogue conversion processing at the timing corresponding tothe reference data of each latch circuit and for outputting it, andoutputs the reference voltage REF corresponding to each segment.

The signal level of a video signal SV outputted from the CCD camera 13is detected and the reference data is registered in the light quantitycorrection memory 16 based on the signal level detection resultpreviously when shipping from a factory. Further when the power sourceis thrown in, the system control circuit 3 sets the reference data inthe reference voltage generation circuit 15. In the fingerprintcollation device 1, if light quantity of the video signal SV isdeficient in the peripheral portion in comparison with the centralportion, for example, in the X-direction as shown in FIG. 6, thereference voltage REF is changed so as to correspond to the change inlight quantity, and thus the image pick-up result is converted correctlyto a binary signal corresponding to convexoconcave of a fingerprint.

To perform the function of the light quantity correction memory 16, thelight quantity correction memory 16 comprises a non-volatile memorywhich is capable of holding the reference data for light quantitycorrection.

(1-1-2) Correction of Threshold Value

Skin contact area varies dependently on pressing force of a finger ontothe base when the finger is placed on the base of the isosceles triangleprism 11. The total signal level varies in the video signal SVdependently on pressing force. In detail as shown in FIGS. 7A to 7C, thetotal signal level decreases so that the range of black level increasesif pressing force is high (refer to FIG. 7A, on the other hand, thetotal signal level increases so that the range of white level increasesif pressing force is low (refer to FIG. 7B). That is true for sweating.By reason of these phenomena, the binary signal S1 varies dependently onpressing force, and fingerprint collation result obtained from thebinary signal S1 is varied in the fingerprint collation device 1.

In the comparison circuit 14, the reference data for light quantitycorrection which is set in the reference voltage generation circuit 15by means of the system control circuit 3 is corrected with reference tocorrection data stored in the threshold value correction memory 24, thereference voltage REF is corrected segment-by-segment correspondingly tothe image pick-up result, thereby the correct binary signal S1 isoutputted even if pressing force and surface condition of the isoscelestriangle prism 11 are changed.

A fingerprint data Di outputted to the data bus BUS is inputtedselectively to the system control circuit 3, the logical level of thefingerprint data D1 is detected in the system control circuit 3, andthen the correction data to be stored in the threshold correction memory24 is set based on the measurement result on the fingerprint data D1 sothat a fall down period T1 of the signal level of the binary signal S1is included in 30 to 70% range of the total period T2 (refer to FIG.7C).

In the comparison circuit 14, the binary signal S1 is outputted usingthe reference voltage REF corrected with reference to the correctiondata, the content of the threshold correction memory 24 is updated forthe binary signal S1, and when the total of the period T1 and T2 of eachsegment is contained in a certain range during repeated series ofprocessing, updating processing of the threshold value correction memory24 comes to an end.

The fingerprint collation device 1 sets the signal level of thereference voltage REF that is a threshold value to the optimal value forevery segments, and outputs the correct collation result even ifpressing force of a finger is changed.

(1-1-3) Changing of Threshold Value

In the fingerprint collation device 1, when the reference voltage REF isset as described herein above, fetching operation of the fingerprintdata D1 and D2 to the fingerprint database 5 or fingerprint collationmemory 6 starts, the comparison circuit 14 outputs the binary signal S1with reference to the reference voltage REF determined dependently onthe reference data of the light quantity correction memory 16 as shownin FIGS. 8A and 8B1, thereafter, outputs successively the binary signalusing the first and second reference voltages REF1 and REF2 which aregenerated by shifting the reference voltage REF to positive side andnegative side by a prescribed voltage (refer to FIGS. 8(A), (B2), and(B3)). In FIGS. 8A and 8B1 to 8B3, the binary signal S1 with nocorrection of light quantity dispersion with reference to the referencevoltage REF is shown.

In the condition that the system control circuit 3 corrects thereference data of the light quantity correction memory 16 dependently onthe content of the threshold value correction memory 24, further thesystem control circuit 3 corrects it by a prescribed value, therebychanging of the reference voltage REF is performed by setting again thereference data in the reference voltage generation circuit 15. Thereby,the fingerprint collation device 1 eliminates deterioration of thefingerprint collation accuracy due to change in pressing force of afinger and in surface condition of the isosceles triangle prism 11, andoutputs a correct collation result.

(1-1-4) Fingerprint Data Output

To output the fingerprint data D1 and D2 as described herein above, thetiming generator 19 generates various clocks for the fingerprintcollation device 1 with reference to the video signal SV, and changesthe clock period to be outputted to the thinning circuit 20 in responseto indication from the system control circuit 3. Thereby, the thinningcircuit 20 changes the thinning proportion dependently on the size of afinger which is addressed for fingerprint collation of the fingerprintdata D1 and D2, in detail, in the case that the finger is small, thefingerprint data D1 and D2 are generated with reduced thinningproportion from the image data DV1 so that fingerprint collation isperformed consistently.

(1-1-5) Pulsatory Wave Detection Section

The pulsatory wave detection section 22 comprises a pressure sensor 23disposed aside from the finger placing position and peripheral circuitsfor outputting the detection result from the pressure sensor 23 to thesystem control circuit 3. The pressure sensor 23 together with apressing mechanism not shown in the drawing presses the sides of afinger in response to an indication from the system control circuit 3when the finger is placed on the finger placing position, and in thiscondition, and outputs the result of detected pulsatory pressurecorresponding to blood flow of the finger.

The detected pressure varies correspondingly to pulsatory motion ofblood flow, and referring to the pulsatory pressure, the system controlcircuit 3 detects the biological reaction of the finger based on thepressure detection result (that is detection result of pulsatory wave).Thereby, the fingerprint collation device 1 executes fingerprintcollation processing and fingerprint collation processing only when thefingerprint collation device 1 judges that a human finger is placed onthe place based on the pressure detection result, thus the security isimproved. In this embodiment, the system control circuit 3 monitors thelogical level of the fingerprint data D1 and D2, and detects a fingerplaced on the place utilizing the change in the logical level as atrigger, thereafter a series of collation processing is started onlywhen the fingerprint collation device judges that a human finger isplaced on the place based on the detection result detected by means ofthe pulsatory detection section 22.

(1-2) Fingerprint Database 5 and Fingerprint Collation Memory 6

(1-2-1) Fingerprint Collation Memory 6

FIG. 9 is a block diagram for illustrating a fingerprint database 5 andfingerprint collation memory 6 with peripheral circuits. The fingerprintcollation memory 6 holds the fingerprint data D1 and D2 outputted fromthe above-mentioned fingerprint data input section 4 when thefingerprint D1 is registered in the fingerprint database 5 and when thefingerprint is collated.

The fingerprint collation memory 6 stores the fingerprint data D1 and D2comprising respectively horizontal 256 pixels and vertical 128 pixelsfrom which 1/2 of the pixels are thinned from pixels of the CCD camera13 for the fingerprint data D1 and D2 inputted from the fingerprint datainput section 4 with a usual thinning proportion by way of addresscontrol which the memory control circuit 30 performs under the controlperformed by the system control circuit 3. On the other hand, in thecase that the thinning proportion is changed dependently on the size ofa finger for inputting, the image formed by the fingerprint data D1 andD2 is partially inputted selectively, then the fingerprint data D1 andD2 comprising horizontal 256 pixels and vertical 128 pixels are storedin the same manner as usual case. Thereby, the fingerprint collationdevice 1 can perform fingerprint collation in the same manner as usualcase on the image which is fetched with a changed thinning proportion.

Further when, the fingerprint collation memory 6 stores the fingerprintdata D1 and D2 outputted from the fingerprint data input section 4 in anerect image memory 6A, and outputs the fingerprint data which is storedsuccessively in the erect image memory 6A through a data bus BUS by wayof address control performed by the memory control circuit 30 to animage rotation circuit 31. Further, the fingerprint collation memory 6stores the fingerprint data D1 of the image which is rotated 90 degreeswith respect to the image based on the original fingerprint dataoutputted from the image rotation circuit 31 in a rotation image memory6B as shown in FIG. 10 and FIG. 11. Thereby, the fingerprint collationdevice 1 can detect the fingerprint collation result by way of the sameprocessing as applied to the original image using the image which wasrotated 90 degrees with respect to the original image.

In detail as shown in FIG. 12, the image rotation circuit 31 comprises8×8 bit flip-flop circuits (FF) 31 AA to 31 HH connected in matrixpattern and a selector 31A, transfers each bit data of the fingerprintdata D1 and D2 inputted from the data bus BUS 8 bytes-by-8 bytessuccessively by means of these flip-flop circuit (FF) 31 AA to 31 HH,thereafter, rotates the arrangement of the fingerprint data D1 and D2 90degrees by way of outputting in parallel bit-by-bit. The image rotationcircuit 31 inputs the fingerprint data D1 and D2 in the unit of asegment each of which segments are indicated with numerals 1 to 512individually as shown in FIG. 13 and then re-stores them in a memorymeans, thereby the image rotation circuit 31 performs processing on thebinary image data in 8 pixel unit, and thus the image rotation circuit31 can rotate not only the arrangement direction of the segments butalso the arrangement direction of the whole image as shown in FIG. 14.

The fingerprint collation memory 6 stores the fingerprint image whichwas rotated 90 degrees with respect to the image stored in the erectimage memory 6A in the rotation image memory 6B.

When the fingerprint data D1 is registered, the fingerprint collationmemory 6 receives and holds a plurality of fingerprint data D1 for oneuser, and the fingerprint collation device 1 selects the bestfingerprint data D1 which is most preferable for fingerprint collationout of these plurality of fingerprint data D1 and registers selectivelyit in the fingerprint database 5.

The memory control circuit 30 performs address control under the controlperformed by the system control circuit 3, thereby the fingerprintcollation memory 6 outputs selectively the fingerprint data D2 which isheld as described herein above through the data bus BUS when thefingerprint is collated and registered in response to the operation ofthe collation rate detection section 7 which will be described hereinafter. Thereby, the fingerprint collation device 1 can cut thefingerprint image in horizontal direction, vertical direction, and slantdirection and can output it.

(1-2-2) Fingerprint Database 5

The fingerprint data base 5 comprises user data which were previouslyregistered and finger print data D1. In detail as shown in FIGS. 15 and16 in the fingerprint data 5, a user ID for each registered user andfingerprint data D11, D12, and D13 of an index finger, middle finger,and little finger respectively for each user ID are registered. If it isdifficult to collate the fingerprint of the middle finger because of,for example, hurt, or if it is difficult to obtain the collation resultof coincidence using the middle finger, the fingerprint collation device1 collates the fingerprint data D2 inputted from the fingerprint datainput section 4 with these fingerprint data D11, D12, and D13 toidentify the person, and thus the fingerprint collation device 1 isadditionally convenient in that point.

The priority data is recorded on each fingerprint data D11, D12, andD13, and a fingerprint is collated successively according to thepriority data. The fingerprint collation device 1 can perform collationwith shorter waiting time for obtaining collation result as a whole, andis improved in convenience for use.

The fingerprint database 5 records the thinning proportion set by thethinning circuit 20 (refer to FIG. 2) when a fingerprint is registeredas a magnification data of each fingerprint data D11, D12, and D13, andthereby fingerprint data D2 is fetched with the correspondingmagnification when the fingerprint data D2 addressed to be collated isinputted. Further the collation rate detected in the fingerprintcollation device 1 is recorded for each user ID, based on the collationrate record the collation condition is varied as required, andre-registration of the fingerprint D11 to D13 is prompted again. Thusthe fingerprint collation device can identify the person consistently.

The fingerprint database 5 outputs selectively the held fingerprint dataD11, D12, and D13 like the fingerprint collation memory 6 by way ofaddress control performed by the memory control circuit 30 which iscontrolled by the system control circuit 3, and the content of thefingerprint database 5 is updated.

The database rotation image memory 5B holds the fingerprint image whichis rotated 90 degrees by the image rotation circuit 31 with respect tothe image of fingerprint data D11, D12, and D13 which are held in thefingerprint database 5. Thereby, the fingerprint collation device 1holds the fingerprint image which was rotated 90 degrees in the rotationimage memory 6B and the database rotation image memory 5Bcorrespondingly to the erect fingerprint image which is held in thefingerprint database 5 and fingerprint collation memory 6, and canperform processing on the image which was rotated 90 degrees as in thesame manner as applied to the original erect image.

(1-3) Collation Rate Detection Section

FIG. 19 is a block diagram for illustrating the collation rate detectionsection 7. The collation rate detection section 7 has 8 series ofcollation sections 40A to 40H, and the target fingerprint data D2addressed to be collated is set partially to each collation section 40Ato 40H. The collation rate detection section 7 supplies successively thefingerprint data D1 to each collation section 40A to 40H so as to scantow-dimensionally on the image of the fingerprint data D1, and detectsthe degree of correlation between the fingerprint data D2 andfingerprint data D1 on each scanning position.

Based on the detection result, the coordinate value with highcorrelation is registered successively in a coordinate group memory 49,and the system control circuit 3 figures out the collation rate withreference to the positional relation of the registered coordinate group,and the judgment of coincidence is derived based on the collation rate.Because individual collation sections 40A to 40H have the samestructure, a collation section 40A is only described in detail anddetailed description of other collation sections 40B to 40H are omittedin FIG. 19. The collation rate detection section 7 detects thecorrelation value of the collation rate between a plurality of images ofthe fingerprint data D1 instead of judgment between the fingerprint dataD1 and D2 when registering.

In the respective collation sections 40B to 40H, the fingerprint data D2stored in the fingerprint collation memory 6 is set 8 bits-by-8 bits inthe latch circuit 41. The fingerprint data D2 to be set in therespective collation sections 40B to 40H is cut into linear images asshown in FIG. 17 by way of address control performed by the memorycontrol circuit 30 (refer to FIG. 9) which is controlled by the systemcontrol circuit 3, and the linear images of the fingerprint data D2 isallocated to the respective collation sections 40B to 40H. That is, thefingerprint data D2 continuous in the horizontal direction, verticaldirection, or slant direction on the original image is allocated.Further in the respective collation sections 40B to 40H, the fingerprintdata D2 which changes in the logical level many times more than aprescribed times in the continuous direction so that the continuousdirection are in parallel by way of previous examination performed bythe system control circuit 3 is allocated.

In the collation sections 40A to 40H, the common fingerprint data D1 issupplied successively to the fingerprint data D2 which are set in therespective collation sections 40B to 40H. When, the fingerprint data D1which is continuous according to the raster scanning order based on theassumption that the direction of image arrangement of the fingerprintdata D2 is the horizontal direction correspondingly to the fingerprintdata D2 which is set to the collation sections 40B to 40H by way ofaddress control performed by the memory control circuit 30 (refer toFIG. 9) which is controlled by the system control circuit 3 is suppliedin 8 bit-by-8 bit.

In the respective collation sections 40A to 40H, the parallel-serialconversion circuit (P/S) 42 converts the fingerprint data D1, which isinputted successively, to the serial data, and outputs it to a shiftregister 43 with a constant period. The shift register 43 holds 64serial data, and performs successively bit shifting synchronously withthe serial data outputted from the parallel-serial conversion circuit42, and outputs the bit shifted data in 64 bit parallel.

A latch circuit 41 outputs the latched 8 byte fingerprint data D2A toD2H in 64 bit parallel. A comparison circuit 44 comprises 64 series ofexclusive-or circuits, and outputs result of comparison of each bitbetween the output data of the shift register 43 and the output data ofthe latch circuit 41.

Thereby, the respective collation sections 40A to 40H performs rasterscanning on the linear images formed by the fingerprint data D2A to D2Hand on the image formed by the fingerprint data D1 as shown in FIG. 18in the case that the fingerprint data D2A to D2H are set so that thepixel values are continuous, for example, in the horizontal direction,and thus judgment of coincidence or no coincidence of each bit betweenoverlapped fingerprint data D1 and D2A to D2H is performed.

A counter 45 counts the 64 series of comparison results obtained asdescribed herein above by the comparison circuit 44, and outputs thecount value. The counter detects the degree of correlation between thelinear image formed by the fingerprint data D2A to D2H and the imageformed by the fingerprint data D1 which is overlapped on the linearimage, and outputs a count value of the value 64 if the overlappedimages are perfectly coincident.

The system control circuit 3 sets the reference value data for judgmentin a register 46, and a comparison circuit 47 compares the referencevalue data set in the register 46 with the count value of the counter45, and outputs judgment data D4A to D4H which rise in signal level ifthe degree of correlation between overlapped fingerprint data D1 and D2Ato D2H is high as the result of raster scanning.

The coordinate group memory 49 corrects and records the address data ADoutputted from the memory control circuit 30 when the judgment data D4Ato D4H rise, and records thereby the relative position informationbetween the fingerprint data D2A to D2H and D1 at the timing of risingof the respective judgment data D4A to D4H for collation sections 40A to40B respectively.

As described herein above, the coordinate group memory 49 performsraster scanning of the linear image on the image of the fingerprint dataD1, and corrects and fetches the address data AD at the timing when thejudgment data rise, and records thereby the position where the degree ofcoincidence between the linear image and the image of the overlappedfingerprint data D1 is high by way of coordinate value of thefingerprint data D1.

In the case of an image having repeated pattern like fingerprint, suchlinear cut image is scanned to judge the degree of correlation betweenoverlapped images, then many points where the degree of coincidence ishigh are found. Therefore, a plurality of coordinate data is recordedfor respective collation sections 40A to 40H in the coordinate groupmemory 49. However in the case that two images belong to different twopersons respectively, coordinate values independent between thecollation sections 40A to 40H are stored in the coordinate group memory49, on the other hand, in the case that two images belong to one person,the relative coordinate values held in relative positional relation ofthe above-mentioned fingerprint data D2A to D2H described for FIG. 17are recorded in the coordinate group memory 49. Utilizing this relation,the collation rate data is generated from the coordinate groupregistered in the coordinate group memory 49.

In the embodiment, the coordinate group memory 49 stores the coordinatedata of the erect image and coordinate data of the rotation imagerespectively in the divided memory areas as shown in FIG. 19. Thecoordinate group memory 49 records the coordinate data detected by meansof the fingerprint data D1 and D2 of the fingerprint database 5 anderect image memory 6A as the coordinate data of the erect image, andrecords the coordinate data detected by means of the fingerprint data D1and D2 of the corresponding database rotation image memory 5B androtation image memory 6B as the coordinate data of the rotation image.

In this embodiment, the fingerprint collation device 1 is structured soas to set the linear images in the respective collation sections 40A to40B with successively changed slant, and the coordinate group memory 49records the coordinate data for each slant angle in the coordinate dataof the erect image and rotation image. Thereby, the fingerprintcollation device 1 judges totally the coordinate data recorded asdescribed herein above to collate the fingerprint, and thus the accuracyof the fingerprint collation is additionally improved.

Further in the embodiment, the coordinate group memory 49 can hold aplurality of series of the coordinate data of such erect image and ofthe coordinate data of the rotation image. The coordinate group memory49 holds the plurality of series corresponding to switching thereference voltage to REF, REF1, or REF2 in the fingerprint data inputsection 4 and corresponding to switching the area where linear imagesare cut (refer to as frame herein after), and records the coordinatedata for each switching of reference voltage and frame respectively.

The fingerprint collation device 1 judges totally the coordinate datawhich are detected correspondingly to the switching of the referencevoltage and to the switching of the frame to improve the collationresults.

(1-4) System Control Circuit

The system control circuit 3 comprises a micro-computer, controls thewhole operation in the fingerprint collation device 1, registers thefingerprint data D1 in the fingerprint database 5, and performsfingerprint collation processing with reference to the fingerprintdatabase 5.

(1-4-1) Correction of Light Quantity Dispersion and Detection ofAbnormality of the Optical System

FIG. 20 is a flowchart for describing roughly the processing sequence ofthe system control circuit 3. When a power source is supplied to thesystem control circuit 3, the sequence proceeds from the step SP1 to thestep SP2, the reference data registered in the light quantity correctionmemory 16 is set in the reference voltage generation circuit 15.Thereby, the system control circuit 3 sets the reference voltage REF ofthe comparison circuit 14 so as to correct light quantity dispersion ofthe optical system, and correct illumination result is obtained with anoptical system having only a simple structure.

Subsequently, the system control circuit 3 executes optical systemoperation ensuring processing in the step SP3. In the optical systemoperation ensuring processing, the system control circuit 3, when thesequence proceeds from the step SP4 to the step SP5, fetches output dataof the serial-parallel conversion circuit 21 through the data bus BUS(refer to FIG. 2) as shown in FIG. 21, and counts the logical levelsegment-by-segment. Counting of the logical level is performed bycounting the number of bits the logical level of which bit falls down.

In the case that a finger is pressed on the base of the isoscelestriangle prism 11 in the fingerprint input section 4, the illuminationlight of the light source 12 is reflected totally on the base for imagepicking up, usually the logical level of the output data is held atH-level. On the other hand, in the case that the base is dirty, theillumination light is reflected irregularly, the brightness level of theimage pick-up result is lowered partially depending on the degree ofsoiling, the logical level falls down to L-level at the correspondingoutput data. Also in the case that the performance of the light source12 is deteriorated in comparison with the performance when shipped fromthe factory to cause serious light quantity dispersion, it becomesdifficult to correct by means of the reference data set in the lightquantity correction memory 16, and the logical level falls down toL-level at the corresponding output data.

The system control circuit 3 judges whether the count value exceeds aprescribed value which is previously set based on the count result inthe subsequent step SP6. If the result is YES, the sequence proceeds tothe step SP7, the system control circuit 3 displays a maintenance callthrough the display section 8, thereafter the sequence proceeds to thestep SP8, the system control circuit 3 finishes this processingsequence. The maintenance call displays a message which presses forcleaning of the finger placing place and a message which presses forinforming to a maintenance worker in the case that a maintenance call isstill displayed after cleaning.

In the fingerprint collation device 1, deterioration of fingerprintaccuracy due to deterioration of performance of the light source andsoiling of the isosceles triangle prism 11 are prevented, and thefingerprint collation accuracy is improved additionally.

On the other hand, if the judgment result is NO, then the system controlcircuit 3 finishes the processing sequence directly in the step SP8.

When the optical system operation ensuring processing is executed asdescribed herein above, the sequence proceeds to the step SP10 (FIG.20), the system control circuit 3 judges whether a finger registrationrequest is inputted. In the embodiment, a fingerprint registrationrequest is inputted by inputting prescribed commands and password numberthrough the key input section 2. The fingerprint data D1 of each user isregistered in the fingerprint database 5 in response to the fingerprintregistration request. If a fingerprint registration request is inputted,then the system control circuit 3 obtains a YES result in the step SP10,the sequence proceeds to the step SP11, the fingerprint registrationprocessing is performed, and the sequence returns to the step SP3.

On the other hand, if a fingerprint registration request is notinputted, then the sequence proceeds from the step 10 to the step 12,the system control circuit 2 judges whether a fingerprint collationrequest is inputted by operating the key input section 2. If thejudgment result is NO, then the sequence of the system control circuit 3returns to the step SP3. On the other hand, if the system controlcircuit 3 detects a fingerprint collation request, then the sequenceproceeds from the step SP12 to the step SP13, the system control circuit3 performs the finger collation processing, and the sequence returns tothe step SP3.

(1-4-2) Fingerprint Registration Processing

FIG. 22 is a flow chart for describing the processing sequence offingerprint registration processing. The sequence proceeds from the stepSP20 to the step SP21, the system control circuit 3 displays a messagethrough the display section 8 (refer to FIG. 1) in the fingerprintregistration processing, and presses a user to place his index finger onthe finger placing place. Subsequently, the sequence proceeds to thestep SP22, the system control circuit 3 judges whether a finger isplaced on the finger placing place, and if the judgment result is NO,then the sequence repeats the step SP22.

In the step SP22, the system control circuit 3 inputs the output data ofthe serial-parallel conversion circuit 21 through the data bus BUS(refer to FIG. 2), and counts the logical level of the output data in asegment unit, thereby detects whether a finger is placed on the fingerplacing place by way of the output data. In the counting processing, thenumber of bits of the logical level is counted for a prescribedplurality of segments at the position corresponding to the approximatelymiddle portion of the finger placing place, and the counting processingis executed by judging whether the count value exceeds a prescribedvalue. Thus the system control circuit 3 performs finger registrationprocessing using image pick-up result as a trigger, and the operation ofthis fingerprint collation device 1 is simplified, and thus theconvenience for use is improved additionally.

If the result is YES in the step SP22, the sequence proceeds to the stepSP23, the system control circuit 3 judges whether the pulsatory wavedetection section 22 detects a biological reaction. If the result is NO,then the sequence proceeds to the step SP24, the system control circuit3 finishes the processing sequence. On the other hand, if the result isYES in the step SP23, the sequence proceeds to the step SP25, the systemcontrol circuit 3 executes actual registration processing that is anactual registration processing. Thereby, the system control circuit 3registers the fingerprint data only when the biological reaction of thefinger is detected, thus the security is improved additionally.

After the actual registration processing is completed, the sequenceproceeds to the step SP26, the system control circuit 3 judges whetherthe fingerprint data is registered including a little finger. In thefingerprint collation device 1, the fingerprint data of an index finger,a middle finger, and a little finger is registered for each user, thesystem control circuit 3 obtains a NO result in the step SP26 as long asa special operation of the user is not detected, the sequence proceedsto the step SP27, the system control circuit 3 presses the user to placethe next finger through the display section 8, and thereafter thesequence returns to the step SP22.

On the other hand, if the registration is completed including a littlefinger, then a YES result is obtained in the step SP26, the sequenceproceeds from the step SP26 to the step SP24, the system control circuit3 finishes the processing sequence.

(1-4-3) Actual Registration Processing

FIG. 23 and FIG. 24 are flowcharts for describing processing sequence ofactual registration processing in the system control circuit 3. Thesequence proceeds from the step SP30 to the step SP31 the system controlcircuit 3 executes detection processing of the effective area in theactual registration processing. As shown in FIG. 25, the sequenceproceeds from the step 32 to the step SP33, the system control circuit 3counts the number of bits of the logical H-level of segment-1, thereby,counts the number of pixels which rise in brightness level in thesegment.

Subsequently, the sequence proceeds to the step SP34, the system controlcircuit 3 judges the count number is less than a prescribed value tojudge whether the area where the brightness level is raised is less thana prescribed value in the target segment. In the optical system of thefingerprint collation device 1, in the case that a finger is placed onthe base (¥1) of the isosceles triangle prism 11, the illumination lightis reflected totally and the corresponding brightness level is raised,and segments having the area more than a prescribed value where thebrightness level rises as described herein above is judged to be blanksegments where a finger is not placed.

If the No result is obtained in the step SP34, then the sequenceproceeds to the step SP35, the system control circuit 3 sets thesesegments to the segments in blank area, thereafter the sequence proceedsto the step SP36. On the other hand, if a YES result is obtained in thestep SP34, then the sequence proceeds to the step SP37, the systemcontrol circuit 3 sets the segments in the effective area, thereafterthe sequence proceeds to the step SP36. Herein the effective area meansthe area where a finger is placed.

In the step SP36, the system control circuit 3 judges whether a seriesof processing on the effective area detection processing is completed onall the segments, and if the No result is obtained, then the sequenceproceeds to the step SP38, the target segment to be subjected to theprocessing is switched to the next segment, and the sequence returns tothe step SP33. On the other hand, if the series of processing iscompleted on all the segments, then the sequence proceeds from the stepSP36 to the step SP39, and returns to the main routine.

As shown in FIG. 26, the system control circuit 3 sets the effectivearea which can be used for finger collation in the image pick-up resultsegment-by-segment, thereafter executes various processing withreference to the effective area, and thereby these various processingare simplified. In the step SP26, segments marked with X are segments inblank area.

Subsequently, the sequence proceeds to the step SP40 (refer to FIG. 23),the system control circuit executes finger position judgment processing.As shown in FIG. 27, the sequence proceeds from the step SP41 to thestep SP42, the system control circuit 3 judges whether the number ofsegments in the effective area is less than a prescribed value. If theNo result is obtained, then the sequence proceeds to the step SP43, thesystem control circuit 3 generates an notice for the user to replace thefinger again through the display section because the place where thefinger is placed is abnormal, and thereafter returns to the detectionprocessing of the effective area.

On the other hand, if a YES result is obtained in the step SP42, thesystem control circuit 3 judges that the place where the finger isplaced is normal, then the sequence proceeds to the step SP44, andreturns to the main routine. Thus the fingerprint collation device 1registers the fingerprint data only when a user places a fingercorrectly, and the fingerprint collation accuracy is improved.

Subsequently, the system control circuit 3 executes zoom processing inthe step SP46. As shown in FIG. 28, in the zoom processing, the sequenceproceeds from the step SP47 to the step SP48, the system control circuit3 judges whether the number of segments in the effective area is lessthan a prescribed value. If the number of segments in the effective areais more than the prescribed value, a finger is image-picked up with asize sufficient for finger collation, then the sequence proceeds fromthe step SP48 to the step SP49, and returns to the main routine.

On the other hand, if a YES result is obtained in the step SP48, thefinger is image-picked up with a size insufficient for fingerprintcollation, then the sequence proceeds to the step SP50, the systemcontrol circuit 3 judges whether the thinning proportion given by thethinning circuit 20 (refer to FIG. 2) can be reduced. If the thinningproportion can be reduced, the sequence proceeds to the step SP51, thesystem control circuit 3 switches the operation of the timing generator19 to reduced the thinning proportion, and enlarges the image of thefingerprint data D1, and then returns to the effective area detectionprocessing in the step SP31.

The system control circuit 3 executes effective area detectionprocessing and finger position inversion processing on the enlargedfingerprint image again, then executes zoom processing. As describedherein above, the fingerprint collation device 1 switches magnificationof the optical system as required and performs fingerprint collationconsistently.

In the case that a finger is dry, the illumination light is notreflected irregularly on the base of the isosceles triangle prism 11(refer to FIG. 2) when the finger is placed. In such case, a No resultmay be obtained in the step SP50 in spite of reduced thinningproportion, and it is difficult to collate the fingerprint correctly. Insuch case, the sequence proceeds to the step SP52, the system controlcircuit 3 outputs a message for confirmation to the user, then finishesa series of fingerprint registration processing in the step SP53. Asdescribed herein above, the fingerprint collation device 1 picks up theimage of fingerprint again and collates the fingerprint consistently insuch unusual case.

Subsequently, the system control circuit 3 executes threshold valuecorrection processing in the step SP55 (refer to FIG. 23). As shown inFIG. 29, in the threshold correction processing, the sequence proceedsfrom the step SP56 to the step SP57, the system control circuit 3 countsthe number of bits of the logical L-level on segment-1. In thisembodiment, brightness level of the corresponding pixel falls down andthe bit of the corresponding fingerprint data D1 falls down to thelogical L-level in the case that the illumination light is reflectedirregularly on the base of the isosceles triangle prism 11, thereby thesystem control circuit 3 detects the area where a finger is pressed onthe base of the isosceles triangle prism 11 based on the count value ofthe number of bits on the target segment.

Subsequently, the sequence proceeds to the step SP58, the system controlcircuit 3 judges whether the count value is included in the range of 30to 70% for the number of pixels (8×8) of the segment. If a NO result isobtained. the fingerprint image is likely strained locally, the sequenceproceeds to the step SP59, the system control circuit 3 updates thecorrection data in the threshold value correction memory is updatedwithin a prescribed range, and then the sequence proceeds to the stepSP60. On the other hand, if a YES result is obtained in the step SP58,then the sequence proceeds directly to the step SP60.

In the step SP60, the system control circuit 3 judges whether a seriesof processing in the threshold value correction processing is finishedfor all the segments set in the effective area, and if a No result isobtained, then the sequence proceeds to the step SP61. The systemcontrol circuit 3 switches the processing target to the next segment,and the sequence returns to the step SP57. On the other hand, if aseries of processing in the threshold value correction processing iscompleted for all the segments, the system control circuit 3 obtains aYES result in the step SP60, then the sequence proceeds to the step SP62and returns to the main routine. Thus the fingerprint collation device 1sets the content of the threshold value correction memory 24 asdescribed herein before for FIG. 6 and performs fingerprint collationconsistently.

Subsequently, in the step SP65 (refer to FIG. 23), the system controlcircuit 3 executes blackening processing. In detail, in the case that afinger is extraordinarily wet, for example, due to sweating, theillumination light is reflected irregularly on the base of the isoscelestriangle prism 11 over a certain area. In such case, brightness level ofpixels corresponding to the target segment remains fallen down in spiteof the reference voltage REF varied within a certain range in theabove-mentioned threshold value correction processing, and a blackenedimage is obtained. Therefore, it is difficult to collate the fingerprinton this segment.

The sequence proceeds from the step SP66 to the step SP67 as shown inFIG. 30, the system control circuit 3 counts the number of bits of thelogical L-level on segment-1, and then the sequence proceeds to the stepSP68, and the system control circuit 3 judges whether the count value issmaller than the prescribed value.

If a No result is obtained, then the sequence proceeds to the step SP68,the system control circuit 3 sets the segment to a blackening segment,and the sequence proceeds to the step SP70. On the other hand, if a YESresult is obtained in the step SP68, then the sequence proceeds directlyto the step SP70. Thus the system control circuit 3 excludes theblackening segment from the processing target in the subsequent seriesof processing, and thus the fingerprint collation accuracy is improved.

In the step SP70, the system control circuit 3 judges whether a seriesof processing in the blackening processing is completed for all thesegment, and if a NO result is obtained, then the sequence proceeds tothe step SP71, the system control circuit 3 sets the next segment in theeffective area to the processing target, and the sequence returns to thestep SP67. The system control circuit 3 detects blackening segments forall the segments in the effective area as described herein above, thenthe sequence proceeds from the step SP70 to the step SP72.

In the step SP72, the system control circuit 3 judges whether the numberof blackening segments is less than a prescribed value. If the number ofblackening segments exceeds a certain value, the number of normalsegments is not sufficient for fingerprint collation, in this case, thesequence proceeds from the step SP72 to the step SP73, the systemcontrol circuit 3 generates a notice to the user to place again afterthe finger is cleaned, and then the sequence returns to the step SP31.

On the other hand, if a YES result is obtained in the step SP72, thenthe sequence proceeds to the step SP74, and returns to the main routine.The fingerprint collation device 1 presses the user to try againfingerprint registration work in the case that the finger is wet, thusonly high quality fingerprint image to be registered is fetched, and thefingerprint collation accuracy is improved additionally.

Subsequently, the sequence proceeds to the step SP80 (refer to FIG. 23),the system control circuit 3 executes angle detection processing. Indetail, a user can place a finger on the finger placing place slant. Thesequence proceeds from the step SP81 to the step SP82, the systemcontrol circuit 3 detects an edge, for example, in Y-direction on theeffective area in the angle detection processing shown in FIG. 31 asshown in FIG. 32. Further, the sequence proceeds to the step SP83 (¥2),the system control circuit 3 detects segments which correspondvertically to the peripheral segments as shown in FIG. 33, and detectssuccessively center coordinates of these segment pairs, and detects aninclination θ of the center line of the fingerprint image.

Subsequently, the sequence proceeds to the step SP84, the system controlcircuit 3 judges whether the angle θ is included within a certain rangeto judge whether the inclination of the finger is smaller than a certainrange, and if a NO result is obtained, the sequence proceeds to the stepSP85, the system control circuit 3 generates a notice to the user toplace the finger correctly, then the sequence returns to the step SP31.If the inclination of the finger is included within the prescribedrange, the sequence proceeds to the step SP86 and returns to the mainroutine.

Thus the fingerprint collation device 1 fetches the fingerprint data D1the inclination of which is included within a certain range, and thefingerprint collation accuracy is improved.

After the previous processing is completed as described herein before,the sequence returns to the step SP88 (refer to FIG. 24), the systemcontrol circuit 3 sets the variable number n for counting the number ofimages to be fetched to 1, and then controls the memory control circuit30 to store the fingerprint data D1 of one image in the fingerprintcollation memory 6 in the step SP89.

Subsequently, the sequence proceeds to the step SP90, the system controlcircuit 3 judges whether the value of the variable n is equal to aprescribed value N, and if a NO result is obtained, then the sequenceproceeds to the step SP91, the variable n is incremented by 1, and thenthe sequence returns to the step SP89. Thus the system control circuit 3repeats the processing sequence of the step SP89-SP90-SP91-SP89 N times,and stores N images in the fingerprint collation memory 6.

Subsequently, the sequence proceeds to the step SP92, the system controlcircuit 3 judges whether the series of processing is completed on thereference voltage REF2, a NO result is obtained in this case, thesequence proceeds to the step SP93, the system control circuit 3performs switching control of the reference voltage in the referencevoltage generation circuit 15, and then the sequence returns to the stepSP88.

The system control circuit 3 stores N images in the fingerprintcollation memory 6 with reference voltage REF which is set by correctingthe reference data stored in the light quantity correction memory 16with the correction data in the threshold value correction memory 24,and then stores N images in the fingerprint collation memory 6 withreference to the reference voltage REF1 that is the reference voltageREF offset to the positive side by a prescribed voltage,

Similarly to the case that the system control circuit 3 fetches N imagewith reference to the reference voltage REF merely by offsetting thereference voltage and by setting the reference voltages REF1 and REF2,the system control circuit 3 inputs N image in the fingerprint collationmemory 6 which was subjected to the light quantity dispersion correctionprocessing (refer to FIG. 20, step SP2) and threshold value correctionprocessing in a segment unit (refer to FIG. 29).

In this reference voltage switching processing, the system controlcircuit 3 counts the logical level of output data outputted from theserial-parallel conversion circuit 21 over the entire effective areaexcluding blackening area, thereby switches the reference voltage sothat the white level area in the area is included in the range of 30 to70% to the whole area. Based on experimental results, a plurality offingerprint image is picked up with the reference voltage switched inthis range and the fingerprint is collated based on the image pick-upresult as described in this embodiment, thereby the fingerprintcollation accuracy is improved.

After input of N images is completed using the reference voltage REF2 asdescribed herein above, the system control circuit 3 obtains a YESresult in the step SP92, and executes registration data selectionprocessing in the step SP93. The registration data selection processinginvolves a processing for judging which fingerprint data D1 should beregistered in the fingerprint database 5 out of 3×N images fetched asdescribed herein above. The system control circuit 3 registers thefingerprint data D1 selected by the registration data selectionprocessing in the step SP94 in the fingerprint database 5, and thenfinishes the processing sequence in the step SP95.

The system control circuit 3 executes the series of processingsuccessively on an index finger, middle finger, and little finger (referto FIG. 22), and registers them in the fingerprint database 5 (refer toFIG. 15) with priority order of from the index finger, to middle finger,and little finger. When, the system control circuit 3 recordsmagnification of the selected fingerprint data D1 (thinning proportioninvolved in the thinning circuit 20). The system control circuit 3 canreproduce the condition at the time when the fingerprint is registeredfor individual fingerprint data D1 in database when a fingerprint iscollated actually, thus the fingerprint collation accuracy is improvedand also the time required for collation is shortened.

(1-4-4) Registration Data Selection Processing

FIG. 34 is a flow chart for describing the above-mentioned registrationdata selection processing, the system control circuit 3 selects afingerprint data D1 to be registered in the fingerprint database 5 outof fingerprint data D1 stored in the fingerprint collation memory 6 byway of this processing sequence.

The sequence proceeds from the step SP100 to the step SP101, the systemcontrol circuit 3 sets the variables n and m to the value of 1 and 2respectively. Herein the variables n and m are variables for specifyingfingerprint data D1 respectively. The system control circuit 3 detectssuccessively the correlation value between fingerprint data specified bythe variable m on the fingerprint data D1 specified by the variable n.Further the system control circuit 3 detects the maximum correlationvalue out of the correlation value detected as described herein above,and sets the fingerprint data D1 with the corresponding variable n asthe fingerprint data D1 to be the registration target.

The system control circuit 3 executes correlation value detectionprocessing in the subsequent step SP102 to detect the correlation valuecorresponding to the fingerprint data D1 with the variable m of thefingerprint data D1 with the variable n. Further, the sequence proceedsto the step SP103, the system control circuit 3 judges whether all thefingerprint data D1 which are fetched in the fingerprint collationmemory 6 is specified with the variable m, and if NO result is obtained,the sequence proceeds to the step SP104, and the system control circuit3 increases the variable m, then the sequence returns to the step SP102.

The system control circuit 3 switches successively the variable m anddetects successively the correlation value between the one fingerprintdata D1 and the other fingerprint data D1 specified with the variable n.

On the other hand, if a YES result is obtained in the step SP103, thenthe sequence proceeds to the step SP105, the system control circuit 3judges whether all the fingerprint data D1 fetched in the fingerprintcollation memory 6 are specified with the variable n. If a NO result isobtained, then the sequence proceeds to the step SP106, the systemcontrol circuit 3 increases the variable n and initializes the variablem to the value of 1, and the sequence returns to the step SP102.

Thus the system control circuit 3 detects the correlation value of thefingerprint data D1 with the variable n on all the combination betweenfingerprint data D1 fetched in the fingerprint collation memory 6.

After the correlation value detection processing is executed on all thecombinations, the system control circuit 3 obtains a YES result in thestep SP105, then the sequence proceeds to the step SP107, the systemcontrol circuit 3 selects the fingerprint data D1 with the maximumcorrelation value with the variable n as a fingerprint data forregistration target, and then the sequence proceeds to the step SP108 tofinish this processing sequence.

In the fingerprint collation device 1, the image quality of thefingerprint image is judged with reference to the correlation value, andthe fingerprint data D1 that is most suitable for fingerprint collationis registered in the fingerprint database 5. In detail, in thefingerprint collation device 1, the fingerprint is collated based on thecollation rate described hereinafter detected by way of the sameprocedure as used for detecting the correlation value. The systemcontrol circuit 3 executes fingerprint collation processing between theresidual fingerprint images on the assumption that a plurality offingerprint images fetched in the fingerprint collation memory 6 isregistered successively in the fingerprint database 5, thereby selectsthe fingerprint image that is suitable for fingerprint collation by wayof the judgment procedure which is suitable for practical fingerprintcollation, and thus the fingerprint collation accuracy is improved.

FIG. 35 is a flow chart for describing correlation value detectionprocessing on the fingerprint data D1 with the variable m of thefingerprint data D1 with the variable n. In the processing sequence, thesequence proceeds from the step SP110 to the step SP111 (¥3), the systemcontrol circuit 3 transmits the fingerprint data D1 specified by thevariables n and m to the image rotation circuit 31 respectivelysegment-by-segment, and stores the fingerprint data outputted from theimage rotation circuit 31 in the rotation image memory 6B. Thereby thesystem control circuit 3 rotates processing target images 90 degreesrespectively in the step SP111 (refer to FIG. 10 and FIG. 11).

Subsequently, the sequence proceeds to the step SP112, the systemcontrol circuit 3 selects intermittently the 8 byte image data whichcontinues in the horizontal direction from the top side of an image ofthe fingerprint data D1 successively out of the fingerprint data D1specified by the variable m. Further the selected fingerprint data areoutputted respectively to the collation sections 40A to 40B, and storedin the latch circuit 41 of the respective collation sections 40A to 40B(refer to FIG. 17). Thereby the system control circuit 3 cuts linearimages from the image of the fingerprint data D1 and sets them in thecollation sections 40A to 40H.

When, the system control circuit 3 executes a prescribed judgmentsequence to set the fingerprint data D1 so as not to cut the linearimage of the blackening segments described for FIG. 30 herein before,and thereby deterioration of the fingerprint collation accuracy isavoided efficiently. The system control circuit 3 sets the area that isthe area where the linear image is cut (namely the frame) with referenceto the effective area detected previously.

The number of switching of the logical level is counted on thefingerprint data to be cut linearly, the portion where the count valueis smaller than a prescribed value is excluded from the target. Thereby,the number of linear cut across a fingerprint is more than a prescribedvalue on the portion where the image is cut linearly, and sufficientinformation useful for fingerprint collation is included in the cutarea, thus the fingerprint collation accuracy is improved.

In connection with the above-mentioned operation, the system controlcircuit 3 sets a frame for cutting linear images in the effective areaat the position with deviation of prescribed some segments from the tipside of the effective area of the tip side portion of a finger to thefoot side of the finger, and sets the frame with reference to the centerof the effective area in the vertical direction.

Subsequently the sequence proceeds to the step SP113, the system controlcircuit 3 transmits successively the fingerprint data to the collationsections 40A to 40H so that the fingerprint data D1 specified with thevariable n is arranged continuous in the order of the raster scanning.The system control circuit 3 scans the linear image in the order of theraster scanning on the image specified with the variable n in therespective collation sections 40A to 40H, and detects the number of bitswhich is coincident between the linear images and the image overlappedwith the linear images with the variable n with aid of the counter 45 ofthe respective collation sections 40A to 40H (refer to FIG. 16).

Further, the system control circuit 3 records the position, where thecount value is similar to the coordinate value which rises from thethreshold value set in the resister 46, that is, where the overlappedtwo images are very similar each other, in the coordinate group memory49 according to the coordinate value of the fingerprint data supplied inthe order of the raster scanning.

When, the system control circuit 3 switches operation of the comparisoncircuit 44 so that the comparison circuit 47 outputs comparison resultbased on a certain logical level on bits corresponding to thefingerprint data which is judged to be blackening area, namelyineffective area, and switches the threshold value to be set in theregister 46 correspondingly to the switching of operation of thecomparison circuit 44, and subsequently changes the criterion in thecomparison circuit 47. Thus the system control circuit 3 performs theprocessing with a mask on the blackening area, namely ineffective area.

The sequence proceeds to the step SP114, the system control circuit 3executes collation rate detection processing. As shown in FIG. 36, FIG.37, and FIG. 38, in the collation rate detection processing, thesequence proceeds from the step SP115 to the step SP116, the systemcontrol circuit 3 sets the variables I, J, K, and Q to the value of 1.Herein, the variables I, J, and K are variables for specifying therespective coordinate values of the collation sections 40A, 40B, and 40Cfetched in the coordinate group memory 49, and the variable Q is thevariable for specifying the combination of these coordinate valuesdetected in the partial collation rate calculation processing.

Subsequently, the sequence proceeds to the step SP117, the systemcontrol circuit 3 sets three combinations comprising a combination of acoordinate value (XIA, YIA) and a coordinate value (XJB, YJB), acombination of a coordinate value (XJB, YJB) and a coordinate value(XKC, YKC), and a combination of a coordinate value (XIA, YIA) and acoordinate value (XKC, YKC) for the three coordinate values (XIA, YIA),(XJB, YJB), and (XKC, YKC) specified with the variables I, J, and K, anddetects the number of combinations which satisfy the relative positionalrelation of the fingerprint data D1 which are set in the latch circuit41 of the respective collation sections 40A to 40C, namely the number ofcombinations which satisfy the relative positional relation of thelinear images which are cut in the step SP 112.

Subsequently, the sequence proceeds to the step SP118, the systemcontrol circuit 3 judges whether the number of combination detected asdescribed herein above is more than a prescribed value M. If a YESresult is obtained, the sequence proceeds to the step SP119, the systemcontrol circuit 3 sets the combinations of I, J, and K as the candidateto be specified with the variable Q, and increases the variable Q in thestep SP120, and the sequence proceeds to the step SP121. On the otherhand, if a NO result (¥4) is obtained in the step SP118, then thesequence proceeds directly from the step SP118 to the step SP121.

In the step SP121, the system control circuit 3 judges whether thecoordinate value specified with the variable K is the coordinate valuethat is detected finally by the collation section 40C, and if a NOresult is obtained, then the sequence proceeds to the step SP122, thesystem control circuit 3 increases the variable K, and the sequencereruns to the step SP117. Thereby the system control circuit 3 switchessuccessively the variable I correspondingly to the coordinate values(XIA, YIA) and (XJB, YJB), and detects successively candidates specifiedwith the variable Q based on the number of combinations which satisfythe relative positional relation of the linear images out ofcombinations of these coordinate values (XIA, YIA), (XJB, YJB), and(XKC, YKC).

When the operation comes to the final coordinate value after successiveswitching of the variable K, the system control circuit 3 obtains a YESresult in the step SP121, then the sequence proceeds to the step SP123.The system control circuit 3 judges whether the coordinate valuespecified with the variable J is the final coordinate value in the samemanner as operated for the variable J, if a NO result is obtained, thenthe sequence proceeds to the step SP124, the system control circuit 3increases the variable J and sets the variable K to the initial value of1, then the sequence returns to the step SP117.

In the step SP123, if the system control circuit 3 obtains YES result byrepeating the processing sequence with increasing the variable J asdescribed herein above, then the sequence proceeds to the step SP125,and the system control circuit 3 judges whether the coordinate valuespecified with the variable I is the final coordinate, and if aNO resultis obtained, then the sequence proceeds to the step SP126, the systemcontrol circuit 3 increases the variable I and sets the variables J andK to the initial value of 1, then the sequence returns to the stepSP117.

The system control circuit 3 excludes combinations which does notsatisfy the relative positional relation the coordinate values obtainedby scanning successively the linear images with aid of the partialcombinations. Thereby in the fingerprint collation device 1,combinations of the detected coordinate values which happens to havehigh similarity are excluded from the candidate, and the residualcombinations are held as the candidate specified with the variable Q.

The system control circuit 3 detects combinations which satisfy therelative positional relation between the candidates selected asdescribed herein above and the coordinate values of the residualcollation sections 40D to 40H in the same manner as operated hereinabove, and detects the collation rate thereby. The system controlcircuit 3 sets the variables Q, L, M, N, O, and P to the initial valueof 1 in the step SP127 (refer to FIG. 37). Herein, the variables L, M,N, O, and P are variables for specifying the coordinate values storedrespectively in the coordinate group memory 49 for the collationsections 40D to 40H.

Subsequently, the sequence proceeds to the step SP128, and the systemcontrol circuit 3 detects the number of combinations which satisfy therelative positional relation of the linear image out of the coordinatevalues (XQA, YQA), (XQB, YQB), (XQC, YQC), (XLD, YLD), (XME, YME), (XNF,YNF), (XOG, YOG), and (XPH, YPH) specified with the variables Q, L, M,N, O, and P.

Subsequently, the sequence proceeds to the step SP129, the systemcontrol circuit 3 records the number of combinations, and then thesequence proceeds to the step SP130. The system control circuit 3 judgeswhether the coordinate value specified with the variable P is the finalcoordinate value, and if a NO result is obtained, the system controlcircuit 3 increases the variable P in the step SP131, and the sequencereturns to the step SP127.

On the other hand, if a YES result is obtained in the step SP130 duringrepetition of the processing sequence, then the sequence proceeds fromthe step SP130 to the step SP132, the system control circuit 3 judgeswhether the coordinate value specified with the variable O is the finalcoordinate value, and if a NO result is obtained, then the sequenceproceeds to the step SP133, the system control circuit 3 increases thevariable O and sets the variable P to the initial value of 1, and thesequence returns to the step SP127.

On the other hand, if a YES result is obtained in the step SP132 duringthe repetition of this processing, then the sequence proceeds from thestep SP132 to the step SP134, the system control 3 circuit 3 judgeswhether the coordinate value specified with the variable N is the finalcoordinate, if a NO result is obtained, then the sequence proceeds tothe step SP135, the system control circuit 3 increases the variable Nand sets the variables P and O to the initial value of 1, and thesequence returns to the step SP127. On the other hand, if a YES resultis obtained in the step SP134, then the sequence proceeds from the stepSP134 to the step SP136, the system control circuit 3 judges whether thecoordinate value specified with the variable M is the final coordinate,if a NO result is obtained, the sequence proceeds to the step SP137, thesystem control circuit 3 increases the variable M and sets the variablesP, O, and N to the initial value of 1, and the sequence returns to thestep SP127.

Further similarly, if a YES result is obtained in the step SP136, thenthe sequence proceeds from the step SP136 to the step SP138, the systemcontrol circuit 3 judges whether the coordinate value specified with thevariable L is the final coordinate value, and if a NO result isobtained, then the sequence proceeds to the step SP137, the systemcontrol circuit 3 increases the variable L and sets the variables P, O,N, and M to the initial value of 1, and the sequence returns to the stepSP127. On the other hand, if a YES result is obtained in the step SP138,then the sequence proceeds from the step SP138 to the step SP140 (referto FIG. 38), the system control circuit 3 judges whether the coordinatevalue specified with the variable Q is the final coordinate value, andif a NO result is obtained, then the sequence proceeds to the stepSP142, the system control circuit 3 increases the variable Q and setsthe variables P, O, M, N, and L to the initial value of 1, and thesequence returns to the step SP127.

The system control circuit 3 detects the number of combinations whichsatisfy the relative positional relation for respective combinations ofthese coordinate values, when, executes this processing after selectingcandidates previously by excluding combinations which does not satisfythe relative positional relation with aid of the partial combinations,thus the time required for processing is shortened additionally. In thecase that a coordinate values are detected for 8 series of coordinatevalues, the number of combinations of these coordinate values is a⁸.

On the other hand, the number of combinations in the previous processingis a³, and in the case that the number of candidate combinations isreduced to the value smaller than a, for example, 1, the number ofresidual combinations is a⁵, after all, a⁵ is extremely larger than a³,the number of combinations to be subjected to processing is reduced byabout a³. For example, assuming a=10, it is found that the time requiredfor processing is reduced by a factor of approximately 1000. Thereforethe fingerprint collation device 1 can executes fingerprint registrationprocessing within a short time.

After the number of combinations which satisfy the relative positionalrelation is detected for the respective combinations as described hereinabove, the system control circuit 3 detects the number of combinationswith the largest value in the step SP142, sets the value of the numberof combinations to the collation rate in the subsequent step SP143, andthe sequence returns from the step SP144 to the main routine. Thus inthis processing, in the case that the coordinate value which satisfiesthe relative positional relation for all the 8 linear images is recordedin the coordinate group memory 49 as for the relative positionalrelation when 8 linear images are cut, the system control circuit 3detects simplified 8/8 collation rate.

Thus, the system control circuit 3 picks up a plurality of fingerprintimages of the same person, cuts image-1 linearly, performs rasterscanning on other images, in this condition, judges totally the degreeof similarity of overlapped portions, and detects the collation rate.

Subsequently, the sequence proceeds to the step SP145 (refer to FIG.35), the system control circuit 3 judges whether the collation rate isdetected on the rotation image generated in the step SP111, and if a NOresult is obtained, then the sequence proceeds to the step SP146, thesystem control circuit 3 switches the processing target to the rotationimage, then the sequence returns to the step SP112, and repeats the sameprocessing.

The system control circuit 3 cuts linear images in the horizontaldirection from fingerprint data-1 stored in the rotation image memory 6Bas shown in FIG. 39 and FIG. 40, and sets these cut fingerprint data ofthe cut images in the collation sections 40A to 40H. The system controlcircuit 3 outputs the corresponding fingerprint data D1 in the order ofraster scanning simultaneously in parallel to the collation sections 40Ato 40H, performs raster scanning of the previous linear images on otherimages, and judges totally the degree of similarity of overlappedportions to detect the collation rate.

In this processing, the system control circuit 3 cuts linear images fromthe fingerprint image inputted from the fingerprint data input section 4in approximately horizontal direction and vertical direction, detectsthe degree of similarity to an image of other fingerprint data in thehorizontal and vertical direction, thus combines the data processing ofthe one-dimensional image which is relatively easy to be subjected toprocessing, and judges the degree of two-dimensional similarity.

After the collation rate is detected on the rotation image as describedherein above, the system control circuit 3 obtains a YES results in thestep SP145, then the sequence proceeds to the step SP147, the systemcontrol circuit 3 sets the collation rate having a value larger thanthat of two collation rates to the correlation value of n image withcollation target of the m image, then the sequence returns from the stepSP148 to the main routine.

Thus, the system control circuit 3 calculates correlation values for allthe combinations between a plurality of finger print images which arepicked up from the same person, selects the fingerprint data with thehighest correlation value, and registers selectively the fingerprintimage that is most useful for fingerprint collation. Thus thefingerprint collation accuracy of the fingerprint collation device 1 isimproved.

(1-4-5) Fingerprint Collation Processing

When a user operates the key input section 2 to input a request forfingerprint collation in the condition that the fingerprint data D1 isregistered in the fingerprint database 5 as described herein above, thesystem control circuit 3 executes processing sequence shown in FIG. 41and FIG. 42 and performs fingerprint collation.

In detail, the sequence proceeds from the step SP150 to the step SP151,the system control circuit 3 displays amessage through the displaysection 8 (refer to FIG. 1) to press a user to place a finger on thefinger placing place. Subsequently, the sequence proceeds to the stepSP152, the system control circuit 3 judges whether a finger is placed onthe finger placing place, and if NO result is obtained, the sequencerepeats the step SP152.

In the step SP152, the system control circuit 3 inputs the output dataof the serial-parallel conversion circuit 21 through the data bus BUS(refer to FIG. 2), counts the logical level of the output data on theprescribed segments, and detects thereby whether a finger is placedthrough the output data. Herein in the count processing, the number ofbits of logical L-level is counted on a plurality of prescribed segmentscorresponding to the approximately middle portion of the finger placingplace, and the processing is performed by judging whether the countvalue exceeds a prescribed value. Thus the system control circuit 3starts fingerprint collation processing with aid of image pick-up resultas a trigger, the operation of the fingerprint collation device 1 issimplified and the convenience for use is improved.

If a YES result is obtained in the step SP152, the sequence proceeds tothe step SP153, the system control circuit 3 judges whether thepulsatory wave detection section 22 detects biological reaction. If a NOresult is obtained, then the sequence proceeds to the step SP154 andthis processing sequence is finished, on the other hand, if a YES resultis obtained in the step SP153, then the sequence proceeds to the stepSP155.

In the step SP155, the system control circuit 3 inputs collation targetfingerprint data D2 outputted from the fingerprint data input section 4to the fingerprint collation memory 6. Thereby the system controlcircuit 3 performs fingerprint collation only when biological reactionof a finger is detected, and the security is improved.

Subsequently, the sequence proceeds to the step SP156, the systemcontrol circuit 3 executes comparison judgment processing. In thisembodiment, the system control circuit 3 judges with reference to theuser ID inputted through the key input section 2 whether the registeredfingerprint data D1 corresponding to the user ID is coincident with thefingerprint data D2 inputted from the fingerprint data input section 4.Further in the case that a plurality of fingerprint data D1 isregistered for the same user ID in the fingerprint database 5, thesystem control circuit 3 judges the coincidence using the fingerprintdata D1 having the highest priority.

Subsequently, the sequence proceeds to the step SP157, the systemcontrol circuit 3 judges whether judgment result of coincidence isobtained, and if a YES result is obtained, then the sequence proceeds tothe step SP158, the system control circuit 3 outputs the judgment resultof coincidence, and the sequence proceeds to the step SP159. The systemcontrol circuit 3 records the collation rate in the fingerprint database5 in the step SP159.

Subsequently, the sequence proceeds to the step SP160 (refer to FIG.42), the system control circuit 3 confirms the change of collation raterecorded in the fingerprint database 5. In the case that the collationrate decreases gradually beyond a certain value, the system controlcircuit 3 judges that the collation rate changes beyond the allowablerange, the sequence proceeds to the step SP161, the system controlcircuit 3 presses a user to register an updated fingerprint data, andfinishes this processing sequence in the step SP162.

In detail, in this embodiment, the degree of similarity is measuredbetween the fingerprint data D2 of a collation target and thefingerprint data D1 registered in the fingerprint database 5, and thedegree of similarity is represented by the collation rate. Coincidencebetween a fingerprint of the fingerprint data D2 and a fingerprint ofthe fingerprint data D1 is judged with reference to the judgment whetherthe collation rate exceeds a certain reference value.

However, in the case of a child, a finger becomes large as the childgrows, in such case, the collation rate decreases gradually as shown inFIG. 43 as the finger grows larger. In this embodiment, when thecollation rate decreases gradually beyond a certain value TH, thefingerprint collation device 1 is set so that the user registers thefingerprint data D2 again, thereby the collation rate is resumed forperforming fingerprint collation consistently.

In the case that such change in the collation rate is not observed, aYES result is obtained in the step SP160 in the system control circuit3, and the sequence proceeds directly from the step SP160 to the stepSP162 to finish this processing sequence. 155

On the other hand, if a NO result is obtained in the step SP157 (referto FIG. 41), the sequence proceeds to the step SP163, the system controlcircuit 3 judges whether the frame is moved already. In this embodiment,as shown in FIG. 44, the system control circuit 3 cuts linear images ina prescribed frame on the fingerprint image of the fingerprint data D1that is the collation target for detecting the collation rate. If thesystem control circuit 3 does not obtain a result of coincidence incomparison judgment processing in the step SP156, then the sequenceproceeds from the step SP163 to the step SP164, the system controlcircuit 3 moves the frame. Further, the sequence returns from the stepSP164 to the step SP156, the system control circuit 3 executescomparison judgment processing with reference to the moved frame.

Thus the system control circuit 3 performs fingerprint collationprocessing so as to obtain the judgment result of coincidenceconsistently in the case that a user who is registered in thefingerprint database 5 collates the fingerprint, thereby the fingerprintcollation accuracy is improved.

In the case that the judgment result of coincidence is not obtainedafter the frame is moved as described herein above, the system controlcircuit 3 obtains a YES result in the step SP163 after the systemcontrol circuit 3 obtains a NO result in the step SP157, then thesequence proceeds to the step SP165 (FIG. 42). Then, the system controlcircuit 3 judges whether another fingerprint data D1 is registered forthe same person.

As described for FIG. 15 herein before, in the case that the fingerprintdata D1 of an index finger, a middle finger, and a little finger isregistered with the priority order data in the fingerprint database 5,the sequence proceeds from the step SP165 to the step SP166, the systemcontrol circuit 3 switches the fingerprint data D1 according to thepriority order, and then the sequence returns to the step SP155. Thesystem control circuit 3 performs fingerprint collation between thefingerprint data D2 inputted from the fingerprint data input section 4and the fingerprint data D11 of an index finger registered in thefingerprint database 5 initially, and subsequently performs fingerprintcollation between the fingerprint data D2 and the fingerprint data of amiddle finger and then the fingerprint data of a little finger, even inthe case that a user places a middle finger instead of an index fingerbecause, for example, the user has a hurt on the index finger, thefingerprint collation device 1 identifies the person consistently. When,by switching successively the fingerprint data D1 according to thepriority order, the time required for fingerprint collation is shortenedadditionally.

If it is difficult to obtained the judgment result of coincidence inspite of switching of the fingerprint data D1 as described herein above,the system control circuit 3 obtains a NO result in the step SP165, andthen the sequence proceeds to the step SP167. The system control circuit3 judges whether the collation rate is smaller than a certain value, ifa YES result is obtained, then the sequence proceeds to the step SP168,the system control circuit 3 outputs a judgment result ofnon-coincidence, and the sequence returns to the step SP162. Thus thesystem control circuit 3 outputs a judgment result of non-coincidenceonly when the system control circuit 3 judges consistently that thetarget fingerprint does not corresponds to the target person.

As described for FIG. 43 herein before for the case of a child, thecollation rate can decrease as a child grows, and in the case thefingerprint has been not collated for long time form the previousfingerprint collation, it is difficult to resume the collation rate byway of the above-mentioned processing in the step SP160, and after all,it is difficult to obtain a judgment result of coincidence. Also in thecase that the fingerprint is defective due to hurt on the finger, it isdifficult to obtain a judgment result of coincidence.

In such case, significant decrease in the collation rate is not observeddifferently from collation with a fingerprint of another person, a NOresult is obtained in the step SP167. Further in such case, by repeatingcollation with the fingerprint data D1, approximately the same degree ofcollation rate is obtained.

In this embodiment, if a NO result is obtained in the step SP167, thenthe sequence proceeds to the step SP169, the system control circuit 3judges whether the series of fingerprint collation is repeated on thesame user ID, and if a NO result is obtained, then the sequence returnsto the step SP151. As described herein above, the system control circuit3 fetches again the fingerprint data D2 and performs fingerprintcollation processing in the case that it is difficult to definitelyjudge it to be coincident or non-coincident. A user can carried outfingerprint collation again with placing, for example, a middle fingerinstead of an index finger.

In this repeated fingerprint collation processing, if a NO result isobtained again in the step SP167, then the system control circuit 3obtains a YES result in the step SP169, the sequence proceeds to thestep SP170, and the system control circuit 3 reduces the criterion forcoincidence judgment, and the sequence returns to the step SP155. In thecase that it is difficult to definitely judge the coincidence afterrepeated processing as described herein above and the collation rate ismaintained in a certain range, a correct judgment result is obtained byjudging it to be coincident, thereby the system control circuit 3 canoutput a judgment result of coincidence consistently.

FIG. 45 is a flowchart for describing fingerprint data input processing.The sequence proceeds from the step SP171 to the step SP172, the systemcontrol circuit 3 executes effective area detection processing. Theeffective area detection processing is performed in the same manner asthe effective area detection processing described for FIG. 25, therebythe system control circuit 3 sets the effective area usable forfingerprint collation in the effective area, thereafter executes variousprocessing with reference to the effective area, and thus these variousprocessing is simplified.

Subsequently, the sequence proceeds to the step SP173, the systemcontrol circuit 3 executes finger position detection processing. Thefinger position detection processing is performed in the same processingsequence as the finger position detection processing described for FIG.27, the system control circuit 3 collates a fingerprint only when a userplaces a finger correctly, thus the fingerprint collation accuracy isimproved.

Subsequently, the sequence proceeds to the step SP174, the systemcontrol circuit 3 executes zoom processing. As shown in FIG. 46, in thezoom processing, the sequence proceeds from the step SP175 to the stepSP176, the system control circuit 3 loads the magnification of thecorresponding fingerprint data D1 from the fingerprint database 5, andin the subsequent step SP177, sets the thinning proportion of thethinning circuit 20 dependently on the loaded magnification, then thesequence proceeds to the step SP178 and returns to the main routine.Thereby the system control circuit 3 fetches the fingerprint data D2 ofthe collation target with reference to the magnification of thefingerprint data D1 registered in the fingerprint database 5, and inputsthe fingerprint data D2 under the same condition as for registration.and thus the fingerprint collation accuracy is improved additionally.

Subsequently, the sequence proceeds to the step SP179 (FIG. 45), thesystem control circuit 3 executes threshold value correction processing,then the sequence proceeds to the step SP180, the system control circuit3 executes blackening processing, and executes angle detectionprocessing in the subsequent step SP181. Further the system controlcircuit 3 inputs the fingerprint data D2 to the erect image memory 6A inthe subsequent step SP182, then the sequence proceeds to the step SP183.The threshold value correction processing, blackening processing, andangle detection processing are performed in the same processing sequenceas corresponding processing described for FIG. 29, FIG. 30, and FIG. 31.Thereby the system control circuit 3 corrects the reference voltage ofthe comparison circuit 14 so as to perform consistently fingerprintcollation, and avoids effectively image deterioration due to soiling ofa finger, and further fetches the fingerprint data D2 with aninclination of the finger.

The system control circuit 3 judges whether the reference voltage REF2is already set in the comparison circuit 14 of the fingerprint datainput section 4, and if a NO result is obtained, then the sequenceproceeds to the step SP184, the system control circuit 3 switches thereference voltage, and the sequence returns to the step SP182. Therebythe system control circuit 3 repeats a processing sequence of the stepSP182-SP183-SP184-SP182, updates successively the reference voltagewhich is the reference for setting the threshold value under thecondition that the reference voltage is corrected by performingthreshold value correction processing, stores the total threefingerprint images in the fingerprint collation memory 6, and thereafterthe sequence proceeds to the step SP185 to finish this processingsequence.

FIG. 47 and FIG. 48 are flow charts for describing processing sequenceof comparison judgment processing. The sequence proceeds from the stepSP190 to the step SP191, the system control circuit 3 transmits thefingerprint data D2 stored in the erect image memory 6A to the imagerotation circuit 31 segment-by-segment, and stores the fingerprint dataoutputted from the image rotation circuit 31 in the rotation imagememory 6B. Further, the system control circuit 3 transmits thecorresponding fingerprint data D1 stored in the fingerprint database 5to the image rotation circuit 31 segment-by-segment, and stores thefingerprint data D1 outputted from the image rotation circuit 31 in thedatabase rotation image memory 5B. Thereby the system control circuit 3rotates the processing target image 90 degrees (refer to FIG. 10 andFIG. 11).

Subsequently, the sequence proceeds to the step SP192, the systemcontrol circuit 3 sets a frame with an inclination by an inclinationangle Δθ which is detected in the above-mentioned angle detectionprocessing (refer to FIG. 45, in step SP181), and sets the frame withcorrection of inclination of a finger as shown in FIG. 49.

In detail, the system control circuit 3 stores 8 pixel data as 1 bytefingerprint data D2 in the fingerprint collation memory 6 as shown inFIG. 50, controls the address of the memory control circuit 30 in 8pixel unit, and cuts successively an image, which is inclinedapproximately by the angle Δθ from the horizontal direction, into linearimages (64 pixels).

Further, the system control circuit 3 outputs the fingerprint data D2Ato D2H which form the linear images cut as described herein above to thecollation sections 40A to 40B respectively, and stores the latch circuitof the respective collation sections 40A to 40B (refer to FIG. 17).Thereby the system control circuit 3 sets the linear images with aninclination with respect to the image of the fingerprint data D1, andthus corrects the inclination of the image of the fingerprint data D2with respect to the image of the fingerprint data D1. Thus, thefingerprint collation device 1 can perform fingerprint collationconsistently even if a user places a finger with inclination within acertain range.

When an image is cut into linear images with setting of a frame asdescribed herein above, the system control circuit 3 executes aprescribed judgment sequence and sets the fingerprint data D2A to D2H sothat blackening segments detected by performing blackening processing(refer to FIG. 45, in the step SP180) are not cut to form liner images,and thereby the fingerprint collation accuracy is prevented fromdeterioration. The frame is set with reference to the previouslydetected effective are to omit the ineffective collation rate detectionprocessing, and the fingerprint collation accuracy is improved.

The system control circuit 3 counts previously the number of switchingof the logical level on the fingerprint data D2A to D2H which are cutlinearly, and excludes the portion where the count value is smaller thana prescribed value from the target. Thereby the line passes across aprescribed number of fingerprints on the portion where these linearimages are cut, information effective for fingerprint collation issufficiently included in the cut area, and thus the fingerprintcollation accuracy is improved. By the way, the system control circuit 3determines the position of a frame in the same manner as used forregistration of fingerprints.

Subsequently, the sequence proceeds to the step SP194, the systemcontrol circuit 3 transmits successively the corresponding fingerprintdata D1 from the fingerprint database 5 to the collation sections 40A to40H so that the fingerprint data D1 continue successively in the orderof raster scanning. Thereby the system control circuit 3 scans thelinear images in the order of raster scanning on an image of thefingerprint data D1 in the respective collation sections 40A to 40H asshown in FIG. 51, and detects the number of bits which is coincidentbetween the liner images and the overlapped image of the fingerprintdata D1 by means of the counter 45 of the respective collation sections40A to 40H (refer to FIG. 16) Further, the system control circuit 3fetches and holds successively coordinate values where the count valuerises beyond the threshold value set in the resister 46, namely theposition which is judged that two overlapped images are very similar, inthe coordinate group memory 49 using the coordinate value of thefingerprint data D1.

When the fingerprint data D1 is outputted from the fingerprint data base5 as described herein above, the system control circuit 3 switchesoperation of the comparison circuit 44 so that the fingerprint database5 outputs the comparative result compared with a certain logical levelfor the corresponding bit of the fingerprint data D1 which is judged tobe an ineffective area namely blackening area, and also switches thethreshold value which is set to the register 46 correspondingly to thechange in the above-mentioned logical level, and changes the criterionused in the subsequent comparison circuit 47. Thus the system controlcircuit 3 performs processing with a mask on such ineffective areas andblackening areas.

Subsequently, the sequence proceeds to the step SP195, the systemcontrol circuit 3 executes collation rate detection processing. Thecollation rate detection processing is executed in the same processingas the collation rate detection processing described for FIG. 36, FIG.37, and FIG. 38.

The system control circuit 3 performs raster scanning of linear imageswhich are cut from the fingerprint data D2 on an image of thefingerprint data D1, and judges totally the degree of similarity of theoverlapped portion to detect the collation rate. When, the systemcontrol circuit 3 forms partial combinations from coordinate valuesobtained by scanning successively the linear images, excludescombinations of coordinate values which have the detected high degree ofsimilarity accidentally, and detects the number of combinations whichsatisfy the relative positional relation between the residualcoordinates. Thus the system control circuit 3 shorten the time requiredfor processing, and performs fingerprint collation within a short time.

Subsequently, the sequence proceeds to the step SP196, the systemcontrol circuit 3 judges whether the angle θ is the final. Herein, thesystem control circuit 3 detects the collation rate a plurality of timesrepeatedly with varying an inclination of the image to be cut intolinear images with the center of the above-mentioned inclinationcorrectionangle Δθ as shown in FIG. 53, and judges totally thecoincidence of the fingerprint with reference to the respectivecollation rate. In this case, the system control circuit 3 obtains a NOresult in the step SP196, updates the angle θ in the step SP197, andthen the sequence returns to the step 193.

Thus the system control circuit 3 cuts an image of the fingerprint dataD1 into linear images with varying successively the angle, and detectsthe collation rate successively using the cut image. The system controlcircuit 3 can performs fingerprint collation consistently even if afingerprint is inclined so severely as it is difficult to correct theinclination by way of angle correction and even if a fingerprint ispartially deformed. In this embodiment, the collation rate is detectedrespectively for 5 angles with the center at the above-mentioned angleΔθ.

After the collation rate is detected respectively for each angle, a YESresult is obtained in the step SP196, then the sequence proceeds to thestep SP198. At this time point, the system control circuit 3 judgeswhether switching of the frame is completed. In this embodiment, threeframes are set continuously, coincidence of the fingerprint is judged oneach frame, and thus the identification capability is improved as shownin FIG. 54.

In this case, a NO result is obtained in the step SP198, then thesequence proceeds to the step SP199, the system control circuit 3switches the frame from frame-1 to frame-2, and then the sequenceproceeds to the step SP193. Thereby the system control circuit 3 detectsthe collation rate of frame-2 in the same manner, and then detects thecollation rate of frame-3 in the same manner.

After the collation rate is detected as described herein above, a YESresult is obtained in the step SP198, and then the sequence proceeds tothe step SP200 (refer to FIG. 48). The system control circuit 3 judgeswhether the same processing is executed on the rotation image stored inthe rotation image memory 6B and the database rotation image memory 5B,and obtains a NO result, then the sequence proceeds to the step SP201.The system control circuit 3 switches the processing target from thefinger print data D1 and D2 held in the erect image memory 6A andfingerprint database 5 respectively which have been the processingtarget heretofore to the fingerprint data D1 and D2 stored in therotation image memory 6B and the database rotation image memory 5B, andthen the sequence returns to the step SP192.

Thus the system control circuit 3 detects successively the collationrate under the condition that the angle is corrected also on the imagewhich is rotated 90 degree with switching the angle successively andswitching the frame successively. Thereby the fingerprint collationdevice 1 can perform fingerprint collation more consistently. In theprocessing, the system control circuit 3 cuts a fingerprint imageoutputted from the fingerprint data input section 4 into linear imagesapproximately in horizontal and vertical direction, detects the degreeof similarity between the linear images and a fingerprint image storedin the fingerprint database, and judges thereby the degree oftwo-dimensional similarity by combining the one-dimensional image dataprocessing which is relatively easy to perform.

After the collation rate is detected as described herein above, a YESresult is obtained in the step SP200, and then the sequence proceeds tothe step SP202. The system control circuit 3 judges whether thedetection processing of the collation rate is completed on all theimages fetched in the fingerprint collation memory 6 after the referencevoltage is switched, and if a NO result is obtained, then the sequenceproceeds to the step SP203, the system control circuit 3 switches theprocessing target image, and the sequence returns to the step SP103.

The system control circuit 3 detects the collation rate of the erectimage and rotation image with switching of the frame and inclination onthree fingerprint images fetched with switching of the referencevoltage.

After the collation rate is detected as described herein above, a YESresult is obtained in the step SP202, then the sequence proceeds to thestep SP204, the system control circuit 3 judges whether the collationrate larger than a prescribed value is obtained on each frame of theerect image. If a YES result is obtained, then the sequence proceeds tothe step SP205, the system control circuit 3 judges whether thecollation rate larger than a prescribed value is obtained on each frameof the rotation image in the same manner.

If a YES result is obtained, the sequence proceeds to the step SP206,and the system control circuit 3 loads coordinate values where acollation rate larger than the prescribed value is detected on the erectimage and rotation image from the coordinate group memory 49. Further,system control circuit 3 judges whether the coordinate values areincluded in a prescribed allowable range. In detail, as shown in FIG. 55and FIG. 56, in the case that the fingerprint is coincident between thefingerprint data D1 and D2, for example, coordinate values (X1, Y1) and(X2, Y2) where a collation rate larger than a prescribed value isdetected by scanning the linear image D2A are the first coordinate whichsatisfies the relative positional relation on the frame in the erectimage and rotation image. By the way, in the case that frame-1 is set atthe same position in the erect image and rotation image for the image ofthe fingerprint data D2, then X-coordinate and Y-coordinate are in therelation of X1=Y2, and Y1=X2.

In the case that the relation is disturbed, when linear image happens tobe scanned in the horizontal or vertical direction, the system controlcircuit 3 can judges it to be another person having the partiallysimilar fingerprint pattern. Thus in this embodiment, identificationcapability of the system control circuit 3 is improved more by way ofthe reference of coordinate value between the erect image and rotationimage.

If a YES result is obtained in the step SP206, then the sequenceproceeds to the step SP207. The system control circuit 3 judges whetherthe coordinate values detected on these frames satisfy the relativepositional relation at the time when the frames are set by judgingwhether the coordinate value detected on the adjacent frame on the erectimage is included in a certain allowable range.

In the case that the fingerprint is identical between the fingerprintdata D1 and D2 as shown in FIG. 57, the coordinate values (X1, Y1) and(X2, Y2) of the fingerprint D1 where a certain collation rate isobtained by scanning with the linear image D2A on each frame correspondsto the initial relation at the time when the frames are set. If therelation is disturbed, when linear image happens to be scanned in thehorizontal or vertical direction, the system control circuit 3 canjudges it to be another person having the partially similar fingerprintpattern. Thus in this embodiment, identification capability of thesystem control circuit 3 is improved more by way of the reference ofcoordinate value between the adjacent frames.

If a YES result is obtained between the adjacent frames on the erectimage as described herein above, the system control circuit 3 executesthe same processing on the adjacent frame of the rotation image, andthereby identification capability is improved more.

In processing in the respective steps from the step SP204 to the stepSP207, the system control circuit 3 judges whether a YES result isobtained respectively on each fingerprint image which is obtained withwitching the angle and reference voltage, and if a YES result isobtained on any image, then the sequence proceeds to the next step.Thereby the system control circuit 3 judges coincidence with the imageof the fingerprint data D1 on the fingerprint images obtained withswitching the angle and reference voltage by way of so calledor-judgment. Thereby the system control circuit 3 avoids thedeterioration of identification capability between the person andanother person, and outputs the result of coincidence consistently inthe case of the person.

If a YES result is obtained in the step SP207 as described herein above,the sequence proceeds from the step SP207 to the step SP208, the systemcontrol circuit 3 judges the fingerprint to be coincident only for thiscase, and the sequence returns from the step SP209 to the main routine.

Thus the system control circuit 3 judges the fingerprint to becoincident only when the fingerprint can be judged to be coincidentconsistently, and thereby the fingerprint collation accuracy isimproved. Further, the processing described for FIG. 42 is repeated asrequired, the system control circuit 3 outputs the judgment ofcoincidence for the user who is judged to be coincident and outputs thedefinite judgment of non-coincidence for the user who is judged to benot coincident.

The above-mentioned update processing of criterion described withreference to FIG. 42 updates the criterion of the above-mentioned stepsof the step SP204 to the step SP207. Similarly, in the recording of thecollation rate in the step SP159 shown in FIG. 41, and in the changejudgment of the collation rate in the step SP160 shown in FIG. 42,collation rates detected for a plurality of frames and inclinations asdescribed herein above are recorded and collation rates recorded arejudged. The judgment of the collation rate in the step SP166 involvesthe repetition of the judgment in the steps from the step SP204 to thestep SP207.

(2) Operation of the Embodiment

In the fingerprint collation device 1 having the structure as describedherein before, the reference data of the light quantity correctionmemory 16 which was set when shipping from a factory is set in thereference voltage generation circuit 15 by way of the control performedby the system control circuit 3 when the power source is thrown in (FIG.2, FIG. 3 to FIGS. 6A and 6B, and FIG. 20), and thereby the referencevoltage of the comparison circuit 14 is set so that the light quantityof the optical system is corrected segment-by-segment. Therebydeterioration of the fingerprint collation accuracy due to lightquantity dispersion of the optical system is effectively avoided, andthe fingerprint collation accuracy can be high with the optical systemhaving a simple structure.

The illumination light emitted from the light source 12 under thiscondition is reflected on the base of the isosceles triangle prism 11, afingerprint is picked up by means of the CCD camera 13, and theimage-picked up result is converted to a binary signal by means of thecomparison circuit 14. The binary signal S1 outputted from thecomparison circuit 14 is latched by means of the latch circuit 18, thebinary signal S1 is converted to a 1 bit image data, thinned by means ofthe thinning circuit 20, and converted to a 8 bit image data in 8 pixelunit by means of the serial-parallel conversion circuit 21.

The image data outputted from the serial-parallel conversion circuit 21as described herein above is inputted to the system control circuit 3through the data bus BUS, and the number of bits where the logical levelfalls down is counted segment-by-segment (refer to FIG. 21), therebyabnormality of the optical system is monitored. Abnormality such assoiling of the base of the isosceles triangle prism 11 which is thefinger placing place and deterioration of the light source 12 isdetected, and maintenance processing is performed as required, thusdeterioration of the fingerprint collation accuracy is avoidedeffectively.

When a user operates the key input section 2 (refer to FIG. 1), thefingerprint collation device 1 executes the corresponding fingerprintregistration processing and fingerprint collation processing (refer toFIG. 20).

In the fingerprint registration processing, the fingerprint collationdevice 1 presses the user to place a finger through the display section8 (refer to FIG. 22), starts finger registration processing in responseto the change in the image data outputted from the serial-parallelconversion circuit 21, thus fingerprint registration is performed withsimple operation.

Subsequently, the pressure sensor 23 (refer to FIG. 2) provided on theside of a finger detects biological reaction of the finger, and ifbiological reaction is not detected, then the fingerprint registrationprocessing is brought to a stop. Thus security is improved in the aspectof fingerprint registration.

On the other hand, if biological reaction is detected, input conditionof the fingerprint data is arranged, thereafter a plurality offingerprint images are taken in, and the image that is most suitable forfingerprint collation is registered in the fingerprint data base 5.

After registration of the index finger is completed in this registrationwork, the fingerprint collation 1 device subsequently registers thefingerprint data D1 of the middle finger, and further subsequently thefingerprint data of the little finger, and priority in the order fromindex finger, to middle finger, and little finger is registered (referto FIG. 15). Thus the fingerprint collation device 1 can performfingerprint collation using any one of an index finger, a middle finger,and a little finger in fingerprint collation processing, and theconvenience for use is improved additionally. The fingerprint collationdevice 1 performs fingerprint collation processing according to thepriority order for fingerprint collation, and the time required forcollation is shortened.

In operation of the fingerprint collation device 1 in the actualprocessing of a pick-up image (refer to FIG. 23), the system controlcircuit 3 counts the output data from the serial-parallel conversioncircuit 21, thereby the area which is formed by picking up image of thebackground is excluded in a segment unit, and only the effective areawhere a fingerprint is picked up actually is detected (refer to FIG.25). Thus the subsequent series of processing is performed withreference to the effective area, and the time required for processing isshortened additionally.

Subsequently, whether the position where the finger is placed is correctis judged based on the number of segments in the effective area (referto FIG. 41), thereby deterioration of collation accuracy due toincorrect placing of the finger is avoided. Further in the subsequentprocessing, the thinning proportion involved in the thinning circuit 20(refer to FIG. 2) is varied based on the number of segments included inthe effective area, thus fingerprint is image picked up with amagnification suitable for fingerprint collation for a small finger, forexample, a finger of a child, and the fingerprint collation accuracy isimproved.

In the subsequent threshold value correction processing (refer to FIG.29), the number of bits of logical H-level is detected segment-bysegment in the effective area, and the area where the finger is placedtightly on the base of the isosceles triangle prism 11 is detected oneach segment in the effective area, and then the content of thethreshold value correction memory 24 (FIG. 2) is corrected so that thecount value of each segment is included in the range from 30 to 70%. Thecontent of the threshold value correction memory 24 is set so that thereference data of the light quantity correction memory 16 is corrected,and thereby deterioration of the fingerprint collation accuracy due tovariation of pressing force of the finger and deterioration of thefingerprint collation accuracy due to soiling of the isosceles triangleprism 11 are avoid effectively in a segment unit.

Subsequently in blackening processing (refer to FIG. 30), the number ofbits of logical L-level is detected segment-by-segment in the effectivearea, thereby blackening segments which is not suitable for fingerprintcollation are detected, and these segments are excluded from thecollation target. Also a finger which is abnormally wet is given anotice. Thus only the image pick-up result performed under conditionsuitable for fingerprint collation is subjected to processing, and thefingerprint collation accuracy is improved.

Subsequently in angle detection processing (refer to FIG. 31, FIG. 32,and FIG. 33), the inclination of a finger is detected with reference tothe effective area, and an notice is given to a user in the case thatthe inclination is abnormal. Thus deterioration of the fingerprintcollation accuracy due to inclined placing of a finger is avoided.

After input condition of the finger data D1 is arranged as describedherein above (refer to FIG. 24) in the fingerprint collation device 1,the fingerprint data D1 outputted from the serial-parallel conversioncircuit 21 for N images is fetched in the erect image memory 6A of thefingerprint collation memory 6 (refer to FIG. 9), subsequently thereference voltage REF of the comparison circuit 14 is offset by aprescribed voltage to the positive side (refer to FIGS. 8A and 8B1 to8B3), and the fingerprint data D1 for N images is fetched in the samemanner in the erect image memory 6A in the erect image memory 6A, andinversely, the reference voltage REF is off-set by a prescribed voltageto the negative side, and the fingerprint data for N images is fetchedin the erect image memory 6A.

By switching the reference voltage to offset, the fingerprint collationdevice 1 equalizes the width of the fingerprint image. The change in thebinary signal S1 due to variation of pressing force, due to deformationof a fingerprint, and due to soiling of the optical system for imagepick-up of a finger is absorbed, and deterioration of the fingerprintcollation accuracy is effectively avoided.

The fingerprint collation device 1 selects an image that is mostsuitable for fingerprint collation out of these 3N fingerprint images,and the selected fingerprint image is registered in the fingerprintdatabase 5. Thereby the fingerprint collation accuracy of thefingerprint collation device 1 is improved.

In the processing for selecting a fingerprint image that is mostsuitable for fingerprint collation (refer to FIG. 34), one of the 3Nimages is assumed to be the fingerprint data registered in thefingerprint database 5, processing for fingerprint collation with otherimages is repeated to detect the collation rate. Further, the sameprocessing is repeated with switching successively the image which isassumed to be registered, the fingerprint image having the maximumcorrelation value, that is the collation rate, is selected and subjectedto execution. Thus the fingerprint collation device 1 selects thefingerprint data D1 to be registered in the fingerprint database 5 usingthe criterion corresponding to the actual fingerprint collation, andfingerprint collation is consistently performed additionally.

In detail, the fingerprint collation device 1 outputs a fingerprint dataassumed to be registered in the fingerprint database 5 (correspond to nimages in FIG. 35) and a fingerprint data (correspond to m images inFIG. 35) which is prepared for detecting the collation rate with theassumed fingerprint data respectively from the erect image memory 6A tothe image rotation circuit 31, and the arrangement in a segment ischanged to generates a fingerprint data where segments are rotated 90degree is generated (refer to FIG. 12). Further, the generatedfingerprint data is stored in the rotation image memory 6B and databaserotation image memory 5B, and thereby the erect image and the rotationimage which is the image formed by rotating the erect image 90 degreeare generated.

8 linear images are cut from m image successively in the verticaldirection each of which linear image is composed of 64 pixel image datain the horizontal direction in the erect image, and the image data ofeach linear image is set in the latch circuit 41 of the respectivecollation sections 40A to 40B (refer to FIG. 16). The fingerprint dataof n image is supplied simultaneously in parallel to the collationsections 40A to 40B so as to be continuous in the order of rasterscanning, and the comparison circuit 44 judges coincidence of each bitbetween two image data.

The counter 45 counts the number of coincident bits, and the comparisoncircuit 47 judges whether the count value exceeds a certain referencevalue. If the count value exceeds a certain value, then the coordinatevalue of the corresponding n image is recorded in the coordinate groupmemory 49 with reference to the address data AD of the memory controlcircuit 30 which outputs the fingerprint data of n image to thecollation section 40A to 40B.

Thereby 8 linear images are subjected respectively to raster scanning onn image (refer to FIG. 18), the degree of similarity is detectedsuccessively between overlapped images, and coordinate values ofpositions where the degree of similarity is larger than a certain valueare stored in the coordinate group memory 49. When, in the fingerprintcollation device 1, scanning of 8 linear images are performedsimultaneously in parallel in 8 sets of the collation sections from 40Ato 40H respectively, thus a fingerprint image suitable for fingerprintcollation is selected within a shorter time.

When such linear images formed by cutting as described herein above areset in the collation sections 40A to 40H, the fingerprint data D1 is setwith aid of a prescribed judgment sequence so that the linear image isnot formed from blackening segments, thereby deterioration of thefingerprint collation accuracy is effectively avoided. Frames from whichlinear images are cut are set with reference to the effective area whichis detected previously, thereby needed images are cut within a shorttime. The number of switching of logical level is counted on thefingerprint data which is cut into linear images, and the portion wherethe count value is smaller than a prescribed value is excluded from thetarget, and the portion which includes sufficiently effectiveinformation is cut, and thus the fingerprint collation accuracy is moreimproved.

On the other hand, the operation of comparison circuits 44 and 47 isswitched so that blackening segment and blank area included in thefingerprint data supplied in the order of raster scanning are coveredwith a mask, thus deterioration of collation rate due to these areas andsegments is effectively avoided.

After the coordinate data of the erect image is held in the coordinategroup memory 49 as described herein above, subsequently the fingerprintdata stored in the rotation image memory 6B and the database rotationimage memory 5B are subjected to the same processing (refer to FIG. 40),and the coordinate data of the rotation image is also recorded (refer toFIG. 19).

The number of combinations which satisfy the relative positionalrelation of the linear image is detected on the coordinate data recordedas described herein above for every combination of the coordinate valuesin the collation sections 40A to 40H by way of collation rate detectionprocessing by means of the system control circuit 3.

When, the system control circuit 3 detects the number of combinationswhich satisfy the relative positional relation of the correspondinglinear image for every combinations of coordinate values obtained fromthe collation sections 40A, 40B, and 40C initially, and coordinatevalues where the high degree of similarity happen to be detected areexcluded with reference to the number of combinations, and the collationrate is detected on the residual combinations. Thereby targets to besubjected to processing is reduced previously with aid of the partialcombinations, and the collation rate is detected within a shorter time,the image suitable for registration is selected within a short time.

After the collation rate is detected on m image on the assumption that nimage is registered in the fingerprint database as described hereinabove, the collation rate is detected with switching the m image, andafter the processing is completed on 3N images, then the n image isswitched and the same processing is repeated, finally the collation rateis detected respectively for each combination.

The collation rate detected as described herein above is dealt as thecorrelation value when fingerprint registration, the fingerprint datawhich gives the largest correlation value when it is assumed to beregistered in the fingerprint database is registered in the fingerprintdatabase 5, thus the fingerprint collation accuracy is improved.

In the fingerprint collation processing, the fingerprint collationdevice 1 presses a user to place a finger (refer to FIG. 41), and startsfingerprint collation processing in response to the change of the imagedata outputted from the serial-parallel conversion circuit 21, and thusfingerprint collation is performed by way of simple operation.

Subsequently, the pressure sensor 23 (refer to FIG. 2) provided on theside of a finger detects biological reaction of a finger, and ifbiological reaction is not detected, then the fingerprint collationprocessing is brought to a stop. Thus the security is improved in theaspect of fingerprint collation.

On the other hand, if biological reaction is detected, then inputcondition for fingerprint data is arranged, thereafter the fingerprintdata is fetched, and fingerprint collation is performed between thefetched fingerprint data and the fingerprint data registered in thefingerprint database 5 for the corresponding user.

In detail, the effective area is detected from the output data of theserial-parallel conversion circuit 21 (refer to FIG. 25) under the inputcondition of the fingerprint data for this fingerprint collation (referto FIG. 45). Thereby subsequent series of processing is performed withreference to the effective area, and the time required for collation isshortened additionally. Whether a finger is placed on the correct placeis judged based on the number of segments in the effective area (referto FIG. 41), and deterioration of collation accuracy due to incorrectplacing of the finger is effectively avoided.

In the subsequent zoom processing (refer to FIG. 46), the thinningproportion to be involved in the thinning circuit 20 is set in thefingerprint data input section 4 so as to correspond to themagnification registered in the fingerprint database 5, thereby thethinning circuit 20 is set so that the fingerprint data is inputted withthe same magnification as that for the fingerprint registration, and thefingerprint collation accuracy is improved.

In the threshold correction processing (refer to FIG. 29), the contentof the threshold correction memory 24 (refer to FIG. 2) is correctedsegment-by-segment in the effective area, thereby deterioration of thefingerprint collation accuracy due to varying pressing force anddeterioration of the fingerprint collation accuracy due to soiling ofthe isosceles triangle prism 11 is avoided effectively in segment unit.Further in the blackening processing (refer to FIG. 30), blackeningsegments which are unsuitable for fingerprint collation are detected,and these segments are excluded from collation target, a notice is givento a user when a finger is moist, and thus an image pick-up result issubjected to processing under the condition suitable for fingerprintcollation, and the fingerprint collation accuracy is improved.

In the subsequent angle detection processing (refer to FIG. 31, FIG. 32,and FIG. 33), the inclination of a finger is detected with reference tothe effective area, a notice is given to a user when the inclination isabnormal, inclination correction processing is performed based on thedetection result when fingerprint collation (refer to FIG. 47, and thestep SP192), and deterioration of the fingerprint collation accuracy dueto inclination of a finger is avoided effectively.

After input condition of the fingerprint data D1 is arranged asdescribed herein above, in the fingerprint collation device 1, thefingerprint data D2 outputted from the serial-parallel conversioncircuit 21 is fetched in the erect image memory 6A of the fingerprintcollation memory 6 (refer to FIG. 9), subsequently the reference voltageREF of the comparison circuit 14 is offset by a prescribed voltage tothe positive side (refer to FIGS. 8A and 8B1 to 8B3), similarly thefingerprint data D2 is fetched in the erect image memory 6A, inverselythe reference voltage REF is offset by a prescribed voltage to thenegative side, and the fingerprint data D2 is fetched in the erect imagememory 6A.

The reference voltage REF is offset and then switched, thereby in thefingerprint collation device 1 the width of collation target fingerprintimage is approximately equalized, and deterioration of the fingerprintcollation accuracy due to varying pressing force and deformedfingerprint is effectively avoided.

The fingerprint data D2 (refer to FIG. 47) fetched in the fingerprintcollation memory 6 as described herein above is outputted from the erectimage memory 6A to the image rotation circuit 31 where the arrangementin segments are changed, and thereafter stored in the rotation imagememory 6B, thereby the rotation image which is the image that the erectimage is rotated 90 degrees is held in the rotation image memory 6B. Onthe other hand, the fingerprint data D1 which is the comparison targetis outputted from the fingerprint database 5 to the image rotationcircuit 31 where the arrangement in segments are changed, thereafterstored in the database rotation image memory 5, and the rotation imagecorresponding to that stored in the rotation image memory 6B isgenerated.

Subsequently, the fingerprint data D2 is inclined by a prescribed anglewith respect to the horizontal direction (refer to FIG. 49 and FIG. 50)so that the inclination detected in the inclination detection processingis corrected, 8 linear images each of which comprises 64 pixel imagedata are cut, the respective linear image data are set in the latchcircuit 41 of the respective collation sections 40A to 40B (refer toFIG. 16). Thereby the inclination of the fingerprint image held in thefingerprint database 5 is corrected, and the fingerprint collationaccuracy is improved. The fingerprint data D1 which is comparison targetin the fingerprint database 5 is supplied simultaneously in parallel tothe collation sections 40A to 40B so as to be continuous in the order ofraster scanning, and the comparison circuit 44 judges the coincidence ofeach bit between these two image data set.

Further the counter 45 counts the number of coincident bits, thecomparison circuit 47 judges whether the count value exceeds a certainreference value. If the count value exceeds a certain value, then thecoordinate data of the corresponding fingerprint data D1 is recorded inthe coordinate group memory 49.

These 8 linear images are subjected respectively to raster scanning onthe image of the fingerprint data D1 (refer to FIG. 51), the degree ofsimilarity is detected successively between overlapped images, andcoordinate data of portions where the degree of similarity exceeds acertain value are stored in the coordinate group memory 49. When, in thefingerprint collation device 1, scanning of these linear images areexecuted simultaneously in parallel in 8 collation sections 40A to 40H,and thus fingerprint collation is performed within a short timeadditionally.

When the cut linear images are set in the collation sections 40A to 40H,the fingerprint data D2 is set so that the linear image is not cut fromblackening segments, and thus deterioration of the fingerprint collationaccuracy is effectively avoided. Frames where the linear images are cutare set, and thus a needed image is cut within a short time. The numberof switching in logical level is counted on the fingerprint data to besubjected to linear cutting, portions where the count value is smallerthan a prescribed value are excluded from the target, thereby only theportion which includes sufficiently useful information for fingerprintcollation is subjected to linear cutting, and thus the fingerprintcollation accuracy is improved.

On the other hand, operation of the comparison circuits 44 and 47 isswitched so that blackening segments and blank areas of the fingerprintdata D1 in the fingerprint database 5 side are masked, and thus thefingerprint collation accuracy is improved.

The coordinate data recorded as described herein above is subjected todetection processing, in the detection processing, the number ofcombinations which satisfy the relative positional relation of thelinear images is detected combination-by-combination of coordinatevalues in the collation sections 40A to 40H by way of the sameprocessing as used for fingerprint registration (refer to FIG. 36 andFIG. 37), and the collation rate is detected based on the detectednumber of combinations. When, in the system control circuit 3,combinations which does not satisfy the relative positional relation inthe partial combinations corresponding to the collation sections 40A to40C are excluded from the processing target, thereby coordinate valuesof the portions where high degree of similarity happens to be detectedare excluded, and the collation rate is detected on the residualcombinations. Thus the collation rate is detected within a short time,and the time required for collation is shortened.

After the collation rate is detected on the inclination correctedfingerprint data D2 as described herein above, subsequently theinclination angle θ is updated (refer to FIG. 53), the same processingis executed, and the same processing is executed with switching theframe (refer to FIG. 54). After the series of processing is completed onthe erect image, the same processing is executed with updatingsuccessively the angle θ and frame on the rotation image (refer to FIG.52). Further, after processing on the erect image and rotation image iscompleted, the same processing is repeated with a switched thresholdvalue on the fingerprint data D2 which is left when it is fetched in thefingerprint collation memory 6 (refer to FIG. 47, and the step SP202 and203)

After a plurality of collation rates are detected corresponding to eachangle and each threshold value of the erect image and rotation image asdescribed herein above, whether the collation rate is larger than acertain value on all the switched frames on the erect image is detected,subsequently whether the collation rate is larger than a certain valueon all the switched frames on the rotation image is detected in the samemanner. Further whether the coordinate values detected on thecorresponding frames on the erect image and rotation image satisfy therelative positional relation is detected, and the same processing isperformed on the switched frames to detect such coordinate values. Inthe case that these all the conditions are satisfied, the fingerprint ofthe fingerprint data D2 is judged to be coincident with the fingerprintof the fingerprint data D1. On the other hand, in the case that any onecondition is not satisfied, the judgment of coincidence is suspended.

By identifying a fingerprint with reference to the erect image androtation image, identification capability is improved. When, by addingthe relative positional relation of coordinate value in the frame to thecriterion, and additionally by adding a condition of adjacent frames,the identification capability is improved additionally.

In the judgment, the coincidence is judged by the logical sum in eachframe of the erect image and rotation image for collation rate obtainedwith the switched angle and reference voltage, thus the identificationcapability is improved for a person registered in the fingerprintdatabase 5, and the result of coincidence is outputted consistently.

In the case that the judgment of coincidence is suspended (refer to FIG.41), a frame which will be a reference is moved (the step SP163), andthe same processing is repeated again. Thus the fingerprint collationaccuracy is improved. Further, in the case that the judgment ofcoincidence is suspended even after moving the frame (refer to FIG. 42),the target fingerprint data D1 is switched according the priority orderif another fingerprint data of the same user is stored (refer to thestep SP165), and the same processing is repeated, and thus thefingerprint collation accuracy is improved additionally.

Further, in the case that the low collation rate smaller than a certainvalue is obtained even after repeating such processing, the fingerprintis judged to be not coincident, and thus the finger print collationaccuracy is improved. On the other hand, in the case that the collationrate is constant within a certain range, the criterion is reduced, andthe same processing is repeated, thereby a person is identifiedconsistently even when the finger is dry abnormally.

On the other hand, in the case that a fingerprint is judged to becoincident, a judgment result is outputted, and thereafter the collationrate of this judgment is recorded in the fingerprint database 5 (referto FIG. 15 and FIG. 41). Subsequently, the historical transition ofcollation rates recorded in the fingerprint database 5 is confirmed, andif the record shows the decreasing trend, then the user is pressed toupdate the recorded fingerprint data (refer to FIG. 43). Thereby thecollation rate is resumed even if the size of a finger has changed, andfinger print collation is performed consistently.

(3) Effect of the Embodiment

According to the structure described herein before, for fingerprintregistration and finger print collation, detected coordinates arecombined partially, combinations of coordinate values on the portionswhere high degree of similarity happen to be detected are excluded fromthe processing target, and the collation rate is detected on theresidual combinations, and thus the collation rate is detectedconsistently within a short time. Therefore, fingerprint collation isperformed consistently within a shorter time. For registration, afingerprint image suitable for fingerprint collation is detected andregistered within a short time.

(4) Other Embodiments

In the embodiment described herein before, the case that the partialcombinations comprising 3 sets of coordinate group are formed from 8sets of coordinate group held in the coordinate memory 49, and thenumber of processing targets is reduced with aid of the partialcombinations, however the present invention is by no means limited tothe case, the number of partial combinations can be set optionally asrequired, the combinations reduced with aid of the partial combinationsmay be further subjected to the processing target reduction with aid ofanother partial combination.

In the above-mentioned embodiment, the case that the coincident of theimage is judged totally with aid of collation rate detected withswitched threshold value, erect image and rotation image, and frame isdescribed, however, the present invention is by no means limited to thecase, and can be applied to the case that these processing is omitted asrequired, the case that some processing out of these processing isexecuted selectively, and the case that the process is executed togetherwith other various judgment methods combinedly.

In the embodiment described herein before, the case that an image to beexamined is cut for fingerprint collation is described, however thepresent invention is by no means limited to the case, and can be appliedwidely to the case that a fingerprint image registered in thefingerprint database is cut for fingerprint collation.

In the embodiment described herein before, that case that the presentinvention is applied as a fingerprint collation device, however thepresent invention is by no means limited to the case, and is applied as,for example, a collation device of stamp (¥7), and an image collationdevice for judging entire or partial similarity or dissimilarity (¥8)between database images.

According to the present invention as described herein, a plurality oflinear images are scanned on another image to detect positions where thedegree of similarity is high, and when the image is collated from therelation of coordinate values of the detected positions, the detectedcoordinate values are partially combined, and combinations which doesnot satisfy the relative positional relation corresponding to the linearimages are excluded from the processing target, thus the number ofcombinations required for processing as a whole is reduced. Thereforecollation result can be obtained consistently within a shorter time.

What is claimed is:
 1. An image collation method for judging coincidencebetween a first image and a second image previous to collationprocessing to determine a correlation between said first and secondimages, comprising the steps of:separating a plurality of partial imagesfrom said first image; comparing each partial image with successiveregions of said second image; generating comparison results betweenoverlapped pixels of said partial images and said successive regions ofsaid second image wherein coordinate values of said partial imageshaving a high degree of similarity between said overlapped pixels of arespective partial image and said second image are detected; selecting aplurality of coordinate values for each partial image to form partialcombinations of said detected coordinate values representing less thanan entire set of combinations of said coordinate values for a particularpartial image; judging coordinate values of each combination formed withreference to the relative positional relation of said partial imageswith respect to the first image to determine the degree of coincidencebetween said first and second images; and excluding from said collationprocessing combinations of coordinate values of which said partialcombinations are judged in said step of judging as having correspondingpartial images of a high decree of similarity such that said collationprocessing is performed on the basis of residual combinations of saidcoordinate values.
 2. The method according to claim 1, wherein selectinga plurality of coordinate values selects, as a partial combination, lessthan a total number of coordinate values for a respective partial image.3. The method according to claim 1, wherein said separating separates,as said partial images, said first image into linear images representinga linear portion of a respective partial image.
 4. The method accordingto claim 1, further comprising the step of imaging a fingerprint imageto be retrieved as said first image.
 5. The method according to claim 4,wherein imaging comprises correcting a light quantity of saidfingerprint image.
 6. The method according to claim 4, wherein imagingcomprises varying an intensity of a signal level of said fingerprintimage in dependence on a finger pressure applied to an imager.
 7. Themethod according to claim 4, wherein imaging comprises varying anintensity of a signal level in dependence with a growth of a finger overtime.
 8. The method according to claim 4, wherein imaging comprisesdetecting said fingerprint image when a pulsatory pressure of a fingerto be imaged is detected.
 9. The method according to claim 4, whereinimaging magnifies the fingerprint image.
 10. The method according toclaim 1, further comprising the step of rotating said first image withrespect to said second image when separating said partial images fromsaid first image.
 11. An image collation apparatus for judgingcoincidence between a first image and a second image previous tocollation processing to determine a correlation between said first andsecond images, comprising:a detection unit for separating a plurality ofpartial images from said first image, comparing each partial image withsuccessive regions of said second image, generating comparison resultsbetween overlapped pixels of said partial images and said successiveregions of said second image, wherein coordinate values of said partialimages having a high degree of similarity between said overlapped pixelsof a respective partial image and said second image are detected,selecting a plurality of detected coordinate values for each partialimage to form combinations of said detected coordinate valuesrepresenting less than an entire set of combinations of said coordinatevalues for a particular partial image, and judging coordinate values ofeach combination with reference to the relative positional relation ofsaid partial images with respect to the first image to determine thedegree of coincidence between said first and second images; and a systemcontroller for excluding from said collation processing combinations ofcoordinate values of which said partial combinations are judged ashaving corresponding partial images of a high decree of similarity suchthat said collation processing is performed on the basis of residualcombinations of said coordinate values.
 12. The apparatus according toclaim 11, wherein said detection unit selects a plurality of coordinatevalues selects, as a partial combination, less than a total number ofcoordinate values for a respective partial image.
 13. The apparatusaccording to claim 11, wherein said detection unit separates, as saidpartial images, said first image into linear images representing alinear portion of a respective partial image.
 14. The apparatusaccording to claim 11, further comprising an imager for imaging afingerprint image as said first image.
 15. The apparatus according toclaim 14, wherein said imager corrects a light quantity of saidfingerprint image.
 16. The apparatus according to claim 14, wherein saidimage varies an intensity of a signal level of said fingerprint image independence on a finger pressure applied to said imager.
 17. Theapparatus according to claim 14, wherein said imager varies an intensityof a signal level in dependence with a growth of a finger over time. 18.The apparatus according to claim 14, wherein said imager detects saidfingerprint image when a pulsatory pressure of a finger to be imaged isdetected.
 19. The apparatus according to claim 14, wherein said imagermagnifies the fingerprint image.
 20. The apparatus according to claim11, wherein said detection unit rotates said first image with respect tosaid second image.